# expression.py # Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010 Michael Bayer mike_mp@zzzcomputing.com # # This module is part of SQLAlchemy and is released under # the MIT License: http://www.opensource.org/licenses/mit-license.php """Defines the base components of SQL expression trees. All components are derived from a common base class :class:`ClauseElement`. Common behaviors are organized based on class hierarchies, in some cases via mixins. All object construction from this package occurs via functions which in some cases will construct composite :class:`ClauseElement` structures together, and in other cases simply return a single :class:`ClauseElement` constructed directly. The function interface affords a more "DSL-ish" feel to constructing SQL expressions and also allows future class reorganizations. Even though classes are not constructed directly from the outside, most classes which have additional public methods are considered to be public (i.e. have no leading underscore). Other classes which are "semi-public" are marked with a single leading underscore; these classes usually have few or no public methods and are less guaranteed to stay the same in future releases. """ import itertools, re from operator import attrgetter from sqlalchemy import util, exc #, types as sqltypes from sqlalchemy.sql import operators from sqlalchemy.sql.visitors import Visitable, cloned_traverse import operator functions, schema, sql_util, sqltypes = None, None, None, None DefaultDialect, ClauseAdapter, Annotated = None, None, None __all__ = [ 'Alias', 'ClauseElement', 'ColumnCollection', 'ColumnElement', 'CompoundSelect', 'Delete', 'FromClause', 'Insert', 'Join', 'Select', 'Selectable', 'TableClause', 'Update', 'alias', 'and_', 'asc', 'between', 'bindparam', 'case', 'cast', 'column', 'delete', 'desc', 'distinct', 'except_', 'except_all', 'exists', 'extract', 'func', 'modifier', 'collate', 'insert', 'intersect', 'intersect_all', 'join', 'label', 'literal', 'literal_column', 'not_', 'null', 'or_', 'outparam', 'outerjoin', 'select', 'subquery', 'table', 'text', 'tuple_', 'union', 'union_all', 'update', ] PARSE_AUTOCOMMIT = util._symbol('PARSE_AUTOCOMMIT') def desc(column): """Return a descending ``ORDER BY`` clause element. e.g.:: order_by = [desc(table1.mycol)] """ return _UnaryExpression(column, modifier=operators.desc_op) def asc(column): """Return an ascending ``ORDER BY`` clause element. e.g.:: order_by = [asc(table1.mycol)] """ return _UnaryExpression(column, modifier=operators.asc_op) def outerjoin(left, right, onclause=None): """Return an ``OUTER JOIN`` clause element. The returned object is an instance of :class:`Join`. Similar functionality is also available via the :func:`outerjoin()` method on any :class:`FromClause`. left The left side of the join. right The right side of the join. onclause Optional criterion for the ``ON`` clause, is derived from foreign key relationships established between left and right otherwise. To chain joins together, use the :func:`join()` or :func:`outerjoin()` methods on the resulting :class:`Join` object. """ return Join(left, right, onclause, isouter=True) def join(left, right, onclause=None, isouter=False): """Return a ``JOIN`` clause element (regular inner join). The returned object is an instance of :class:`Join`. Similar functionality is also available via the :func:`join()` method on any :class:`FromClause`. left The left side of the join. right The right side of the join. onclause Optional criterion for the ``ON`` clause, is derived from foreign key relationships established between left and right otherwise. To chain joins together, use the :func:`join()` or :func:`outerjoin()` methods on the resulting :class:`Join` object. """ return Join(left, right, onclause, isouter) def select(columns=None, whereclause=None, from_obj=[], **kwargs): """Returns a ``SELECT`` clause element. Similar functionality is also available via the :func:`select()` method on any :class:`FromClause`. The returned object is an instance of :class:`Select`. All arguments which accept :class:`ClauseElement` arguments also accept string arguments, which will be converted as appropriate into either :func:`text()` or :func:`literal_column()` constructs. columns A list of :class:`ClauseElement` objects, typically :class:`ColumnElement` objects or subclasses, which will form the columns clause of the resulting statement. For all members which are instances of :class:`Selectable`, the individual :class:`ColumnElement` members of the :class:`Selectable` will be added individually to the columns clause. For example, specifying a :class:`~sqlalchemy.schema.Table` instance will result in all the contained :class:`~sqlalchemy.schema.Column` objects within to be added to the columns clause. This argument is not present on the form of :func:`select()` available on :class:`~sqlalchemy.schema.Table`. whereclause A :class:`ClauseElement` expression which will be used to form the ``WHERE`` clause. from_obj A list of :class:`ClauseElement` objects which will be added to the ``FROM`` clause of the resulting statement. Note that "from" objects are automatically located within the columns and whereclause ClauseElements. Use this parameter to explicitly specify "from" objects which are not automatically locatable. This could include :class:`~sqlalchemy.schema.Table` objects that aren't otherwise present, or :class:`Join` objects whose presence will supercede that of the :class:`~sqlalchemy.schema.Table` objects already located in the other clauses. \**kwargs Additional parameters include: autocommit Deprecated. Use .execution_options(autocommit=) to set the autocommit option. prefixes a list of strings or :class:`ClauseElement` objects to include directly after the SELECT keyword in the generated statement, for dialect-specific query features. distinct=False when ``True``, applies a ``DISTINCT`` qualifier to the columns clause of the resulting statement. use_labels=False when ``True``, the statement will be generated using labels for each column in the columns clause, which qualify each column with its parent table's (or aliases) name so that name conflicts between columns in different tables don't occur. The format of the label is _. The "c" collection of the resulting :class:`Select` object will use these names as well for targeting column members. for_update=False when ``True``, applies ``FOR UPDATE`` to the end of the resulting statement. Certain database dialects also support alternate values for this parameter, for example mysql supports "read" which translates to ``LOCK IN SHARE MODE``, and oracle supports "nowait" which translates to ``FOR UPDATE NOWAIT``. correlate=True indicates that this :class:`Select` object should have its contained :class:`FromClause` elements "correlated" to an enclosing :class:`Select` object. This means that any :class:`ClauseElement` instance within the "froms" collection of this :class:`Select` which is also present in the "froms" collection of an enclosing select will not be rendered in the ``FROM`` clause of this select statement. group_by a list of :class:`ClauseElement` objects which will comprise the ``GROUP BY`` clause of the resulting select. having a :class:`ClauseElement` that will comprise the ``HAVING`` clause of the resulting select when ``GROUP BY`` is used. order_by a scalar or list of :class:`ClauseElement` objects which will comprise the ``ORDER BY`` clause of the resulting select. limit=None a numerical value which usually compiles to a ``LIMIT`` expression in the resulting select. Databases that don't support ``LIMIT`` will attempt to provide similar functionality. offset=None a numeric value which usually compiles to an ``OFFSET`` expression in the resulting select. Databases that don't support ``OFFSET`` will attempt to provide similar functionality. bind=None an ``Engine`` or ``Connection`` instance to which the resulting ``Select ` object will be bound. The ``Select`` object will otherwise automatically bind to whatever ``Connectable`` instances can be located within its contained :class:`ClauseElement` members. """ return Select(columns, whereclause=whereclause, from_obj=from_obj, **kwargs) def subquery(alias, *args, **kwargs): """Return an :class:`Alias` object derived from a :class:`Select`. name alias name \*args, \**kwargs all other arguments are delivered to the :func:`select` function. """ return Select(*args, **kwargs).alias(alias) def insert(table, values=None, inline=False, **kwargs): """Return an :class:`Insert` clause element. Similar functionality is available via the :func:`insert()` method on :class:`~sqlalchemy.schema.Table`. :param table: The table to be inserted into. :param values: A dictionary which specifies the column specifications of the ``INSERT``, and is optional. If left as None, the column specifications are determined from the bind parameters used during the compile phase of the ``INSERT`` statement. If the bind parameters also are None during the compile phase, then the column specifications will be generated from the full list of table columns. Note that the :meth:`~Insert.values()` generative method may also be used for this. :param prefixes: A list of modifier keywords to be inserted between INSERT and INTO. Alternatively, the :meth:`~Insert.prefix_with` generative method may be used. :param inline: if True, SQL defaults will be compiled 'inline' into the statement and not pre-executed. If both `values` and compile-time bind parameters are present, the compile-time bind parameters override the information specified within `values` on a per-key basis. The keys within `values` can be either :class:`~sqlalchemy.schema.Column` objects or their string identifiers. Each key may reference one of: * a literal data value (i.e. string, number, etc.); * a Column object; * a SELECT statement. If a ``SELECT`` statement is specified which references this ``INSERT`` statement's table, the statement will be correlated against the ``INSERT`` statement. """ return Insert(table, values, inline=inline, **kwargs) def update(table, whereclause=None, values=None, inline=False, **kwargs): """Return an :class:`Update` clause element. Similar functionality is available via the :func:`update()` method on :class:`~sqlalchemy.schema.Table`. :param table: The table to be updated. :param whereclause: A :class:`ClauseElement` describing the ``WHERE`` condition of the ``UPDATE`` statement. Note that the :meth:`~Update.where()` generative method may also be used for this. :param values: A dictionary which specifies the ``SET`` conditions of the ``UPDATE``, and is optional. If left as None, the ``SET`` conditions are determined from the bind parameters used during the compile phase of the ``UPDATE`` statement. If the bind parameters also are None during the compile phase, then the ``SET`` conditions will be generated from the full list of table columns. Note that the :meth:`~Update.values()` generative method may also be used for this. :param inline: if True, SQL defaults will be compiled 'inline' into the statement and not pre-executed. If both `values` and compile-time bind parameters are present, the compile-time bind parameters override the information specified within `values` on a per-key basis. The keys within `values` can be either :class:`~sqlalchemy.schema.Column` objects or their string identifiers. Each key may reference one of: * a literal data value (i.e. string, number, etc.); * a Column object; * a SELECT statement. If a ``SELECT`` statement is specified which references this ``UPDATE`` statement's table, the statement will be correlated against the ``UPDATE`` statement. """ return Update( table, whereclause=whereclause, values=values, inline=inline, **kwargs) def delete(table, whereclause = None, **kwargs): """Return a :class:`Delete` clause element. Similar functionality is available via the :func:`delete()` method on :class:`~sqlalchemy.schema.Table`. :param table: The table to be updated. :param whereclause: A :class:`ClauseElement` describing the ``WHERE`` condition of the ``UPDATE`` statement. Note that the :meth:`~Delete.where()` generative method may be used instead. """ return Delete(table, whereclause, **kwargs) def and_(*clauses): """Join a list of clauses together using the ``AND`` operator. The ``&`` operator is also overloaded on all :class:`_CompareMixin` subclasses to produce the same result. """ if len(clauses) == 1: return clauses[0] return BooleanClauseList(operator=operators.and_, *clauses) def or_(*clauses): """Join a list of clauses together using the ``OR`` operator. The ``|`` operator is also overloaded on all :class:`_CompareMixin` subclasses to produce the same result. """ if len(clauses) == 1: return clauses[0] return BooleanClauseList(operator=operators.or_, *clauses) def not_(clause): """Return a negation of the given clause, i.e. ``NOT(clause)``. The ``~`` operator is also overloaded on all :class:`_CompareMixin` subclasses to produce the same result. """ return operators.inv(_literal_as_binds(clause)) def distinct(expr): """Return a ``DISTINCT`` clause.""" expr = _literal_as_binds(expr) return _UnaryExpression(expr, operator=operators.distinct_op, type_=expr.type) def between(ctest, cleft, cright): """Return a ``BETWEEN`` predicate clause. Equivalent of SQL ``clausetest BETWEEN clauseleft AND clauseright``. The :func:`between()` method on all :class:`_CompareMixin` subclasses provides similar functionality. """ ctest = _literal_as_binds(ctest) return ctest.between(cleft, cright) def case(whens, value=None, else_=None): """Produce a ``CASE`` statement. whens A sequence of pairs, or alternatively a dict, to be translated into "WHEN / THEN" clauses. value Optional for simple case statements, produces a column expression as in "CASE WHEN ..." else\_ Optional as well, for case defaults produces the "ELSE" portion of the "CASE" statement. The expressions used for THEN and ELSE, when specified as strings, will be interpreted as bound values. To specify textual SQL expressions for these, use the literal_column() or text() construct. The expressions used for the WHEN criterion may only be literal strings when "value" is present, i.e. CASE table.somecol WHEN "x" THEN "y". Otherwise, literal strings are not accepted in this position, and either the text() or literal() constructs must be used to interpret raw string values. Usage examples:: case([(orderline.c.qty > 100, item.c.specialprice), (orderline.c.qty > 10, item.c.bulkprice) ], else_=item.c.regularprice) case(value=emp.c.type, whens={ 'engineer': emp.c.salary * 1.1, 'manager': emp.c.salary * 3, }) Using :func:`literal_column()`, to allow for databases that do not support bind parameters in the ``then`` clause. The type can be specified which determines the type of the :func:`case()` construct overall:: case([(orderline.c.qty > 100, literal_column("'greaterthan100'", String)), (orderline.c.qty > 10, literal_column("'greaterthan10'", String)) ], else_=literal_column("'lethan10'", String)) """ return _Case(whens, value=value, else_=else_) def cast(clause, totype, **kwargs): """Return a ``CAST`` function. Equivalent of SQL ``CAST(clause AS totype)``. Use with a :class:`~sqlalchemy.types.TypeEngine` subclass, i.e:: cast(table.c.unit_price * table.c.qty, Numeric(10,4)) or:: cast(table.c.timestamp, DATE) """ return _Cast(clause, totype, **kwargs) def extract(field, expr): """Return the clause ``extract(field FROM expr)``.""" return _Extract(field, expr) def collate(expression, collation): """Return the clause ``expression COLLATE collation``.""" expr = _literal_as_binds(expression) return _BinaryExpression( expr, _literal_as_text(collation), operators.collate, type_=expr.type) def exists(*args, **kwargs): """Return an ``EXISTS`` clause as applied to a :class:`Select` object. Calling styles are of the following forms:: # use on an existing select() s = select([table.c.col1]).where(table.c.col2==5) s = exists(s) # construct a select() at once exists(['*'], **select_arguments).where(criterion) # columns argument is optional, generates "EXISTS (SELECT *)" # by default. exists().where(table.c.col2==5) """ return _Exists(*args, **kwargs) def union(*selects, **kwargs): """Return a ``UNION`` of multiple selectables. The returned object is an instance of :class:`CompoundSelect`. A similar :func:`union()` method is available on all :class:`FromClause` subclasses. \*selects a list of :class:`Select` instances. \**kwargs available keyword arguments are the same as those of :func:`select`. """ return CompoundSelect(CompoundSelect.UNION, *selects, **kwargs) def union_all(*selects, **kwargs): """Return a ``UNION ALL`` of multiple selectables. The returned object is an instance of :class:`CompoundSelect`. A similar :func:`union_all()` method is available on all :class:`FromClause` subclasses. \*selects a list of :class:`Select` instances. \**kwargs available keyword arguments are the same as those of :func:`select`. """ return CompoundSelect(CompoundSelect.UNION_ALL, *selects, **kwargs) def except_(*selects, **kwargs): """Return an ``EXCEPT`` of multiple selectables. The returned object is an instance of :class:`CompoundSelect`. \*selects a list of :class:`Select` instances. \**kwargs available keyword arguments are the same as those of :func:`select`. """ return CompoundSelect(CompoundSelect.EXCEPT, *selects, **kwargs) def except_all(*selects, **kwargs): """Return an ``EXCEPT ALL`` of multiple selectables. The returned object is an instance of :class:`CompoundSelect`. \*selects a list of :class:`Select` instances. \**kwargs available keyword arguments are the same as those of :func:`select`. """ return CompoundSelect(CompoundSelect.EXCEPT_ALL, *selects, **kwargs) def intersect(*selects, **kwargs): """Return an ``INTERSECT`` of multiple selectables. The returned object is an instance of :class:`CompoundSelect`. \*selects a list of :class:`Select` instances. \**kwargs available keyword arguments are the same as those of :func:`select`. """ return CompoundSelect(CompoundSelect.INTERSECT, *selects, **kwargs) def intersect_all(*selects, **kwargs): """Return an ``INTERSECT ALL`` of multiple selectables. The returned object is an instance of :class:`CompoundSelect`. \*selects a list of :class:`Select` instances. \**kwargs available keyword arguments are the same as those of :func:`select`. """ return CompoundSelect(CompoundSelect.INTERSECT_ALL, *selects, **kwargs) def alias(selectable, alias=None): """Return an :class:`Alias` object. An :class:`Alias` represents any :class:`FromClause` with an alternate name assigned within SQL, typically using the ``AS`` clause when generated, e.g. ``SELECT * FROM table AS aliasname``. Similar functionality is available via the :func:`alias()` method available on all :class:`FromClause` subclasses. selectable any :class:`FromClause` subclass, such as a table, select statement, etc.. alias string name to be assigned as the alias. If ``None``, a random name will be generated. """ return Alias(selectable, alias=alias) def literal(value, type_=None): """Return a literal clause, bound to a bind parameter. Literal clauses are created automatically when non- :class:`ClauseElement` objects (such as strings, ints, dates, etc.) are used in a comparison operation with a :class:`_CompareMixin` subclass, such as a :class:`~sqlalchemy.schema.Column` object. Use this function to force the generation of a literal clause, which will be created as a :class:`_BindParamClause` with a bound value. :param value: the value to be bound. Can be any Python object supported by the underlying DB-API, or is translatable via the given type argument. :param type\_: an optional :class:`~sqlalchemy.types.TypeEngine` which will provide bind-parameter translation for this literal. """ return _BindParamClause(None, value, type_=type_, unique=True) def tuple_(*expr): """Return a SQL tuple. Main usage is to produce a composite IN construct:: tuple_(table.c.col1, table.c.col2).in_( [(1, 2), (5, 12), (10, 19)] ) """ return _Tuple(*expr) def label(name, obj): """Return a :class:`_Label` object for the given :class:`ColumnElement`. A label changes the name of an element in the columns clause of a ``SELECT`` statement, typically via the ``AS`` SQL keyword. This functionality is more conveniently available via the :func:`label()` method on :class:`ColumnElement`. name label name obj a :class:`ColumnElement`. """ return _Label(name, obj) def column(text, type_=None): """Return a textual column clause, as would be in the columns clause of a ``SELECT`` statement. The object returned is an instance of :class:`ColumnClause`, which represents the "syntactical" portion of the schema-level :class:`~sqlalchemy.schema.Column` object. text the name of the column. Quoting rules will be applied to the clause like any other column name. For textual column constructs that are not to be quoted, use the :func:`literal_column` function. type\_ an optional :class:`~sqlalchemy.types.TypeEngine` object which will provide result-set translation for this column. """ return ColumnClause(text, type_=type_) def literal_column(text, type_=None): """Return a textual column expression, as would be in the columns clause of a ``SELECT`` statement. The object returned supports further expressions in the same way as any other column object, including comparison, math and string operations. The type\_ parameter is important to determine proper expression behavior (such as, '+' means string concatenation or numerical addition based on the type). text the text of the expression; can be any SQL expression. Quoting rules will not be applied. To specify a column-name expression which should be subject to quoting rules, use the :func:`column` function. type\_ an optional :class:`~sqlalchemy.types.TypeEngine` object which will provide result-set translation and additional expression semantics for this column. If left as None the type will be NullType. """ return ColumnClause(text, type_=type_, is_literal=True) def table(name, *columns): """Return a :class:`TableClause` object. This is a primitive version of the :class:`~sqlalchemy.schema.Table` object, which is a subclass of this object. """ return TableClause(name, *columns) def bindparam(key, value=None, type_=None, unique=False, required=False): """Create a bind parameter clause with the given key. value a default value for this bind parameter. a bindparam with a value is called a ``value-based bindparam``. type\_ a sqlalchemy.types.TypeEngine object indicating the type of this bind param, will invoke type-specific bind parameter processing unique if True, bind params sharing the same name will have their underlying ``key`` modified to a uniquely generated name. mostly useful with value-based bind params. required A value is required at execution time. """ if isinstance(key, ColumnClause): return _BindParamClause(key.name, value, type_=key.type, unique=unique, required=required) else: return _BindParamClause(key, value, type_=type_, unique=unique, required=required) def outparam(key, type_=None): """Create an 'OUT' parameter for usage in functions (stored procedures), for databases which support them. The ``outparam`` can be used like a regular function parameter. The "output" value will be available from the :class:`~sqlalchemy.engine.ResultProxy` object via its ``out_parameters`` attribute, which returns a dictionary containing the values. """ return _BindParamClause( key, None, type_=type_, unique=False, isoutparam=True) def text(text, bind=None, *args, **kwargs): """Create literal text to be inserted into a query. When constructing a query from a :func:`select()`, :func:`update()`, :func:`insert()` or :func:`delete()`, using plain strings for argument values will usually result in text objects being created automatically. Use this function when creating textual clauses outside of other :class:`ClauseElement` objects, or optionally wherever plain text is to be used. text the text of the SQL statement to be created. use ``:`` to specify bind parameters; they will be compiled to their engine-specific format. bind an optional connection or engine to be used for this text query. autocommit=True Deprecated. Use .execution_options(autocommit=) to set the autocommit option. bindparams a list of :func:`bindparam()` instances which can be used to define the types and/or initial values for the bind parameters within the textual statement; the keynames of the bindparams must match those within the text of the statement. The types will be used for pre-processing on bind values. typemap a dictionary mapping the names of columns represented in the ``SELECT`` clause of the textual statement to type objects, which will be used to perform post-processing on columns within the result set (for textual statements that produce result sets). """ return _TextClause(text, bind=bind, *args, **kwargs) def null(): """Return a :class:`_Null` object, which compiles to ``NULL`` in a sql statement. """ return _Null() class _FunctionGenerator(object): """Generate :class:`Function` objects based on getattr calls.""" def __init__(self, **opts): self.__names = [] self.opts = opts def __getattr__(self, name): # passthru __ attributes; fixes pydoc if name.startswith('__'): try: return self.__dict__[name] except KeyError: raise AttributeError(name) elif name.endswith('_'): name = name[0:-1] f = _FunctionGenerator(**self.opts) f.__names = list(self.__names) + [name] return f def __call__(self, *c, **kwargs): o = self.opts.copy() o.update(kwargs) if len(self.__names) == 1: global functions if functions is None: from sqlalchemy.sql import functions func = getattr(functions, self.__names[-1].lower(), None) if func is not None: return func(*c, **o) return Function( self.__names[-1], packagenames=self.__names[0:-1], *c, **o) # "func" global - i.e. func.count() func = _FunctionGenerator() # "modifier" global - i.e. modifier.distinct # TODO: use UnaryExpression for this instead ? modifier = _FunctionGenerator(group=False) class _generated_label(unicode): """A unicode subclass used to identify dynamically generated names.""" def _escape_for_generated(x): if isinstance(x, _generated_label): return x else: return x.replace('%', '%%') def _clone(element): return element._clone() def _expand_cloned(elements): """expand the given set of ClauseElements to be the set of all 'cloned' predecessors. """ return itertools.chain(*[x._cloned_set for x in elements]) def _select_iterables(elements): """expand tables into individual columns in the given list of column expressions. """ return itertools.chain(*[c._select_iterable for c in elements]) def _cloned_intersection(a, b): """return the intersection of sets a and b, counting any overlap between 'cloned' predecessors. The returned set is in terms of the enties present within 'a'. """ all_overlap = set(_expand_cloned(a)).intersection(_expand_cloned(b)) return set(elem for elem in a if all_overlap.intersection(elem._cloned_set)) def _is_literal(element): return not isinstance(element, Visitable) and \ not hasattr(element, '__clause_element__') def _from_objects(*elements): return itertools.chain(*[element._from_objects for element in elements]) def _labeled(element): if not hasattr(element, 'name'): return element.label(None) else: return element def _column_as_key(element): if isinstance(element, basestring): return element if hasattr(element, '__clause_element__'): element = element.__clause_element__() return element.key def _literal_as_text(element): if hasattr(element, '__clause_element__'): return element.__clause_element__() elif not isinstance(element, Visitable): return _TextClause(unicode(element)) else: return element def _clause_element_as_expr(element): if hasattr(element, '__clause_element__'): return element.__clause_element__() else: return element def _literal_as_column(element): if hasattr(element, '__clause_element__'): return element.__clause_element__() elif not isinstance(element, Visitable): return literal_column(str(element)) else: return element def _literal_as_binds(element, name=None, type_=None): if hasattr(element, '__clause_element__'): return element.__clause_element__() elif not isinstance(element, Visitable): if element is None: return null() else: return _BindParamClause(name, element, type_=type_, unique=True) else: return element def _type_from_args(args): for a in args: if not isinstance(a.type, sqltypes.NullType): return a.type else: return sqltypes.NullType def _no_literals(element): if hasattr(element, '__clause_element__'): return element.__clause_element__() elif not isinstance(element, Visitable): raise exc.ArgumentError("Ambiguous literal: %r. Use the 'text()' " "function to indicate a SQL expression " "literal, or 'literal()' to indicate a " "bound value." % element) else: return element def _corresponding_column_or_error(fromclause, column, require_embedded=False): c = fromclause.corresponding_column(column, require_embedded=require_embedded) if c is None: raise exc.InvalidRequestError( "Given column '%s', attached to table '%s', " "failed to locate a corresponding column from table '%s'" % (column, getattr(column, 'table', None),fromclause.description) ) return c @util.decorator def _generative(fn, *args, **kw): """Mark a method as generative.""" self = args[0]._generate() fn(self, *args[1:], **kw) return self def is_column(col): """True if ``col`` is an instance of :class:`ColumnElement`.""" return isinstance(col, ColumnElement) class ClauseElement(Visitable): """Base class for elements of a programmatically constructed SQL expression. """ __visit_name__ = 'clause' _annotations = {} supports_execution = False _from_objects = [] _bind = None def _clone(self): """Create a shallow copy of this ClauseElement. This method may be used by a generative API. Its also used as part of the "deep" copy afforded by a traversal that combines the _copy_internals() method. """ c = self.__class__.__new__(self.__class__) c.__dict__ = self.__dict__.copy() c.__dict__.pop('_cloned_set', None) # this is a marker that helps to "equate" clauses to each other # when a Select returns its list of FROM clauses. the cloning # process leaves around a lot of remnants of the previous clause # typically in the form of column expressions still attached to the # old table. c._is_clone_of = self return c @util.memoized_property def _cloned_set(self): """Return the set consisting all cloned anscestors of this ClauseElement. Includes this ClauseElement. This accessor tends to be used for FromClause objects to identify 'equivalent' FROM clauses, regardless of transformative operations. """ s = util.column_set() f = self while f is not None: s.add(f) f = getattr(f, '_is_clone_of', None) return s def __getstate__(self): d = self.__dict__.copy() d.pop('_is_clone_of', None) return d if util.jython: def __hash__(self): """Return a distinct hash code. ClauseElements may have special equality comparisons which makes us rely on them having unique hash codes for use in hash-based collections. Stock __hash__ doesn't guarantee unique values on platforms with moving GCs. """ return id(self) def _annotate(self, values): """return a copy of this ClauseElement with the given annotations dictionary. """ global Annotated if Annotated is None: from sqlalchemy.sql.util import Annotated return Annotated(self, values) def _deannotate(self): """return a copy of this ClauseElement with an empty annotations dictionary. """ return self._clone() def unique_params(self, *optionaldict, **kwargs): """Return a copy with :func:`bindparam()` elments replaced. Same functionality as ``params()``, except adds `unique=True` to affected bind parameters so that multiple statements can be used. """ return self._params(True, optionaldict, kwargs) def params(self, *optionaldict, **kwargs): """Return a copy with :func:`bindparam()` elments replaced. Returns a copy of this ClauseElement with :func:`bindparam()` elements replaced with values taken from the given dictionary:: >>> clause = column('x') + bindparam('foo') >>> print clause.compile().params {'foo':None} >>> print clause.params({'foo':7}).compile().params {'foo':7} """ return self._params(False, optionaldict, kwargs) def _params(self, unique, optionaldict, kwargs): if len(optionaldict) == 1: kwargs.update(optionaldict[0]) elif len(optionaldict) > 1: raise exc.ArgumentError( "params() takes zero or one positional dictionary argument") def visit_bindparam(bind): if bind.key in kwargs: bind.value = kwargs[bind.key] if unique: bind._convert_to_unique() return cloned_traverse(self, {}, {'bindparam':visit_bindparam}) def compare(self, other, **kw): """Compare this ClauseElement to the given ClauseElement. Subclasses should override the default behavior, which is a straight identity comparison. \**kw are arguments consumed by subclass compare() methods and may be used to modify the criteria for comparison. (see :class:`ColumnElement`) """ return self is other def _copy_internals(self, clone=_clone): """Reassign internal elements to be clones of themselves. Called during a copy-and-traverse operation on newly shallow-copied elements to create a deep copy. """ pass def get_children(self, **kwargs): """Return immediate child elements of this :class:`ClauseElement`. This is used for visit traversal. \**kwargs may contain flags that change the collection that is returned, for example to return a subset of items in order to cut down on larger traversals, or to return child items from a different context (such as schema-level collections instead of clause-level). """ return [] def self_group(self, against=None): return self # TODO: remove .bind as a method from the root ClauseElement. # we should only be deriving binds from FromClause elements # and certain SchemaItem subclasses. # the "search_for_bind" functionality can still be used by # execute(), however. @property def bind(self): """Returns the Engine or Connection to which this ClauseElement is bound, or None if none found. """ if self._bind is not None: return self._bind for f in _from_objects(self): if f is self: continue engine = f.bind if engine is not None: return engine else: return None def execute(self, *multiparams, **params): """Compile and execute this :class:`ClauseElement`.""" e = self.bind if e is None: label = getattr(self, 'description', self.__class__.__name__) msg = ('This %s is not bound and does not support direct ' 'execution. Supply this statement to a Connection or ' 'Engine for execution. Or, assign a bind to the statement ' 'or the Metadata of its underlying tables to enable ' 'implicit execution via this method.' % label) raise exc.UnboundExecutionError(msg) return e._execute_clauseelement(self, multiparams, params) def scalar(self, *multiparams, **params): """Compile and execute this :class:`ClauseElement`, returning the result's scalar representation. """ return self.execute(*multiparams, **params).scalar() def compile(self, bind=None, dialect=None, **kw): """Compile this SQL expression. The return value is a :class:`~sqlalchemy.engine.Compiled` object. Calling ``str()`` or ``unicode()`` on the returned value will yield a string representation of the result. The :class:`~sqlalchemy.engine.Compiled` object also can return a dictionary of bind parameter names and values using the ``params`` accessor. :param bind: An ``Engine`` or ``Connection`` from which a ``Compiled`` will be acquired. This argument takes precedence over this :class:`ClauseElement`'s bound engine, if any. :param column_keys: Used for INSERT and UPDATE statements, a list of column names which should be present in the VALUES clause of the compiled statement. If ``None``, all columns from the target table object are rendered. :param dialect: A ``Dialect`` instance frmo which a ``Compiled`` will be acquired. This argument takes precedence over the `bind` argument as well as this :class:`ClauseElement`'s bound engine, if any. :param inline: Used for INSERT statements, for a dialect which does not support inline retrieval of newly generated primary key columns, will force the expression used to create the new primary key value to be rendered inline within the INSERT statement's VALUES clause. This typically refers to Sequence execution but may also refer to any server-side default generation function associated with a primary key `Column`. """ if not dialect: if bind: dialect = bind.dialect elif self.bind: dialect = self.bind.dialect bind = self.bind else: global DefaultDialect if DefaultDialect is None: from sqlalchemy.engine.default import DefaultDialect dialect = DefaultDialect() compiler = self._compiler(dialect, bind=bind, **kw) compiler.compile() return compiler def _compiler(self, dialect, **kw): """Return a compiler appropriate for this ClauseElement, given a Dialect.""" return dialect.statement_compiler(dialect, self, **kw) def __str__(self): # Py3K #return unicode(self.compile()) # Py2K return unicode(self.compile()).encode('ascii', 'backslashreplace') # end Py2K def __and__(self, other): return and_(self, other) def __or__(self, other): return or_(self, other) def __invert__(self): return self._negate() def __nonzero__(self): raise TypeError("Boolean value of this clause is not defined") def _negate(self): if hasattr(self, 'negation_clause'): return self.negation_clause else: return _UnaryExpression( self.self_group(against=operators.inv), operator=operators.inv, negate=None) def __repr__(self): friendly = getattr(self, 'description', None) if friendly is None: return object.__repr__(self) else: return '<%s.%s at 0x%x; %s>' % ( self.__module__, self.__class__.__name__, id(self), friendly) class _Immutable(object): """mark a ClauseElement as 'immutable' when expressions are cloned.""" def unique_params(self, *optionaldict, **kwargs): raise NotImplementedError("Immutable objects do not support copying") def params(self, *optionaldict, **kwargs): raise NotImplementedError("Immutable objects do not support copying") def _clone(self): return self class Operators(object): def __and__(self, other): return self.operate(operators.and_, other) def __or__(self, other): return self.operate(operators.or_, other) def __invert__(self): return self.operate(operators.inv) def op(self, opstring): def op(b): return self.operate(operators.op, opstring, b) return op def operate(self, op, *other, **kwargs): raise NotImplementedError(str(op)) def reverse_operate(self, op, other, **kwargs): raise NotImplementedError(str(op)) class ColumnOperators(Operators): """Defines comparison and math operations.""" timetuple = None """Hack, allows datetime objects to be compared on the LHS.""" def __lt__(self, other): return self.operate(operators.lt, other) def __le__(self, other): return self.operate(operators.le, other) __hash__ = Operators.__hash__ def __eq__(self, other): return self.operate(operators.eq, other) def __ne__(self, other): return self.operate(operators.ne, other) def __gt__(self, other): return self.operate(operators.gt, other) def __ge__(self, other): return self.operate(operators.ge, other) def __neg__(self): return self.operate(operators.neg) def concat(self, other): return self.operate(operators.concat_op, other) def like(self, other, escape=None): return self.operate(operators.like_op, other, escape=escape) def ilike(self, other, escape=None): return self.operate(operators.ilike_op, other, escape=escape) def in_(self, other): return self.operate(operators.in_op, other) def startswith(self, other, **kwargs): return self.operate(operators.startswith_op, other, **kwargs) def endswith(self, other, **kwargs): return self.operate(operators.endswith_op, other, **kwargs) def contains(self, other, **kwargs): return self.operate(operators.contains_op, other, **kwargs) def match(self, other, **kwargs): return self.operate(operators.match_op, other, **kwargs) def desc(self): return self.operate(operators.desc_op) def asc(self): return self.operate(operators.asc_op) def collate(self, collation): return self.operate(operators.collate, collation) def __radd__(self, other): return self.reverse_operate(operators.add, other) def __rsub__(self, other): return self.reverse_operate(operators.sub, other) def __rmul__(self, other): return self.reverse_operate(operators.mul, other) def __rdiv__(self, other): return self.reverse_operate(operators.div, other) def between(self, cleft, cright): return self.operate(operators.between_op, cleft, cright) def distinct(self): return self.operate(operators.distinct_op) def __add__(self, other): return self.operate(operators.add, other) def __sub__(self, other): return self.operate(operators.sub, other) def __mul__(self, other): return self.operate(operators.mul, other) def __div__(self, other): return self.operate(operators.div, other) def __mod__(self, other): return self.operate(operators.mod, other) def __truediv__(self, other): return self.operate(operators.truediv, other) def __rtruediv__(self, other): return self.reverse_operate(operators.truediv, other) class _CompareMixin(ColumnOperators): """Defines comparison and math operations for :class:`ClauseElement` instances.""" def __compare(self, op, obj, negate=None, reverse=False, **kwargs): if obj is None or isinstance(obj, _Null): if op == operators.eq: return _BinaryExpression(self, null(), operators.is_, negate=operators.isnot) elif op == operators.ne: return _BinaryExpression(self, null(), operators.isnot, negate=operators.is_) else: raise exc.ArgumentError("Only '='/'!=' operators can be used with NULL") else: obj = self._check_literal(op, obj) if reverse: return _BinaryExpression(obj, self, op, type_=sqltypes.BOOLEANTYPE, negate=negate, modifiers=kwargs) else: return _BinaryExpression(self, obj, op, type_=sqltypes.BOOLEANTYPE, negate=negate, modifiers=kwargs) def __operate(self, op, obj, reverse=False): obj = self._check_literal(op, obj) if reverse: left, right = obj, self else: left, right = self, obj if left.type is None: op, result_type = sqltypes.NULLTYPE._adapt_expression(op, right.type) elif right.type is None: op, result_type = left.type._adapt_expression(op, sqltypes.NULLTYPE) else: op, result_type = left.type._adapt_expression(op, right.type) return _BinaryExpression(left, right, op, type_=result_type) # a mapping of operators with the method they use, along with their negated # operator for comparison operators operators = { operators.add : (__operate,), operators.mul : (__operate,), operators.sub : (__operate,), # Py2K operators.div : (__operate,), # end Py2K operators.mod : (__operate,), operators.truediv : (__operate,), operators.lt : (__compare, operators.ge), operators.le : (__compare, operators.gt), operators.ne : (__compare, operators.eq), operators.gt : (__compare, operators.le), operators.ge : (__compare, operators.lt), operators.eq : (__compare, operators.ne), operators.like_op : (__compare, operators.notlike_op), operators.ilike_op : (__compare, operators.notilike_op), } def operate(self, op, *other, **kwargs): o = _CompareMixin.operators[op] return o[0](self, op, other[0], *o[1:], **kwargs) def reverse_operate(self, op, other, **kwargs): o = _CompareMixin.operators[op] return o[0](self, op, other, reverse=True, *o[1:], **kwargs) def in_(self, other): return self._in_impl(operators.in_op, operators.notin_op, other) def _in_impl(self, op, negate_op, seq_or_selectable): seq_or_selectable = _clause_element_as_expr(seq_or_selectable) if isinstance(seq_or_selectable, _ScalarSelect): return self.__compare( op, seq_or_selectable, negate=negate_op) elif isinstance(seq_or_selectable, _SelectBaseMixin): # TODO: if we ever want to support (x, y, z) IN (select x, y, z from table), # we would need a multi-column version of as_scalar() to produce a multi- # column selectable that does not export itself as a FROM clause return self.__compare( op, seq_or_selectable.as_scalar(), negate=negate_op) elif isinstance(seq_or_selectable, Selectable): return self.__compare( op, seq_or_selectable, negate=negate_op) # Handle non selectable arguments as sequences args = [] for o in seq_or_selectable: if not _is_literal(o): if not isinstance( o, _CompareMixin): raise exc.InvalidRequestError( "in() function accepts either a list of non-selectable values, " "or a selectable: %r" % o) else: o = self._bind_param(op, o) args.append(o) if len(args) == 0: # Special case handling for empty IN's, behave like comparison # against zero row selectable. We use != to build the # contradiction as it handles NULL values appropriately, i.e. # "not (x IN ())" should not return NULL values for x. util.warn("The IN-predicate on \"%s\" was invoked with an empty sequence. " "This results in a contradiction, which nonetheless can be " "expensive to evaluate. Consider alternative strategies for " "improved performance." % self) return self != self return self.__compare(op, ClauseList(*args).self_group(against=op), negate=negate_op) def __neg__(self): return _UnaryExpression(self, operator=operators.neg) def startswith(self, other, escape=None): """Produce the clause ``LIKE '%'``""" # use __radd__ to force string concat behavior return self.__compare( operators.like_op, literal_column("'%'", type_=sqltypes.String).__radd__( self._check_literal(operators.like_op, other) ), escape=escape) def endswith(self, other, escape=None): """Produce the clause ``LIKE '%'``""" return self.__compare( operators.like_op, literal_column("'%'", type_=sqltypes.String) + self._check_literal(operators.like_op, other), escape=escape) def contains(self, other, escape=None): """Produce the clause ``LIKE '%%'``""" return self.__compare( operators.like_op, literal_column("'%'", type_=sqltypes.String) + self._check_literal(operators.like_op, other) + literal_column("'%'", type_=sqltypes.String), escape=escape) def match(self, other): """Produce a MATCH clause, i.e. ``MATCH ''`` The allowed contents of ``other`` are database backend specific. """ return self.__compare(operators.match_op, self._check_literal(operators.match_op, other)) def label(self, name): """Produce a column label, i.e. `` AS ``. if 'name' is None, an anonymous label name will be generated. """ return _Label(name, self, self.type) def desc(self): """Produce a DESC clause, i.e. `` DESC``""" return desc(self) def asc(self): """Produce a ASC clause, i.e. `` ASC``""" return asc(self) def distinct(self): """Produce a DISTINCT clause, i.e. ``DISTINCT ``""" return _UnaryExpression(self, operator=operators.distinct_op, type_=self.type) def between(self, cleft, cright): """Produce a BETWEEN clause, i.e. `` BETWEEN AND ``""" return _BinaryExpression( self, ClauseList( self._check_literal(operators.and_, cleft), self._check_literal(operators.and_, cright), operator=operators.and_, group=False), operators.between_op) def collate(self, collation): """Produce a COLLATE clause, i.e. `` COLLATE utf8_bin``""" return collate(self, collation) def op(self, operator): """produce a generic operator function. e.g.:: somecolumn.op("*")(5) produces:: somecolumn * 5 :param operator: a string which will be output as the infix operator between this :class:`ClauseElement` and the expression passed to the generated function. This function can also be used to make bitwise operators explicit. For example:: somecolumn.op('&')(0xff) is a bitwise AND of the value in somecolumn. """ return lambda other: self.__operate(operator, other) def _bind_param(self, operator, obj): return _BindParamClause(None, obj, _compared_to_operator=operator, _compared_to_type=self.type, unique=True) def _check_literal(self, operator, other): if isinstance(other, _BindParamClause) and \ isinstance(other.type, sqltypes.NullType): # TODO: perhaps we should not mutate the incoming bindparam() # here and instead make a copy of it. this might # be the only place that we're mutating an incoming construct. other.type = self.type return other elif hasattr(other, '__clause_element__'): return other.__clause_element__() elif not isinstance(other, ClauseElement): return self._bind_param(operator, other) elif isinstance(other, (_SelectBaseMixin, Alias)): return other.as_scalar() else: return other class ColumnElement(ClauseElement, _CompareMixin): """Represent an element that is usable within the "column clause" portion of a ``SELECT`` statement. This includes columns associated with tables, aliases, and subqueries, expressions, function calls, SQL keywords such as ``NULL``, literals, etc. :class:`ColumnElement` is the ultimate base class for all such elements. :class:`ColumnElement` supports the ability to be a *proxy* element, which indicates that the :class:`ColumnElement` may be associated with a :class:`Selectable` which was derived from another :class:`Selectable`. An example of a "derived" :class:`Selectable` is an :class:`Alias` of a :class:`~sqlalchemy.schema.Table`. A :class:`ColumnElement`, by subclassing the :class:`_CompareMixin` mixin class, provides the ability to generate new :class:`ClauseElement` objects using Python expressions. See the :class:`_CompareMixin` docstring for more details. """ __visit_name__ = 'column' primary_key = False foreign_keys = [] quote = None _label = None @property def _select_iterable(self): return (self, ) @util.memoized_property def base_columns(self): return util.column_set(c for c in self.proxy_set if not hasattr(c, 'proxies')) @util.memoized_property def proxy_set(self): s = util.column_set([self]) if hasattr(self, 'proxies'): for c in self.proxies: s.update(c.proxy_set) return s def shares_lineage(self, othercolumn): """Return True if the given :class:`ColumnElement` has a common ancestor to this :class:`ColumnElement`.""" return bool(self.proxy_set.intersection(othercolumn.proxy_set)) def _make_proxy(self, selectable, name=None): """Create a new :class:`ColumnElement` representing this :class:`ColumnElement` as it appears in the select list of a descending selectable. """ if name: co = ColumnClause(name, selectable, type_=getattr(self, 'type', None)) else: name = str(self) co = ColumnClause(self.anon_label, selectable, type_=getattr(self, 'type', None)) co.proxies = [self] selectable.columns[name] = co return co def compare(self, other, use_proxies=False, equivalents=None, **kw): """Compare this ColumnElement to another. Special arguments understood: :param use_proxies: when True, consider two columns that share a common base column as equivalent (i.e. shares_lineage()) :param equivalents: a dictionary of columns as keys mapped to sets of columns. If the given "other" column is present in this dictionary, if any of the columns in the correponding set() pass the comparison test, the result is True. This is used to expand the comparison to other columns that may be known to be equivalent to this one via foreign key or other criterion. """ to_compare = (other, ) if equivalents and other in equivalents: to_compare = equivalents[other].union(to_compare) for oth in to_compare: if use_proxies and self.shares_lineage(oth): return True elif oth is self: return True else: return False @util.memoized_property def anon_label(self): """provides a constant 'anonymous label' for this ColumnElement. This is a label() expression which will be named at compile time. The same label() is returned each time anon_label is called so that expressions can reference anon_label multiple times, producing the same label name at compile time. the compiler uses this function automatically at compile time for expressions that are known to be 'unnamed' like binary expressions and function calls. """ return _generated_label("%%(%d %s)s" % (id(self), getattr(self, 'name', 'anon'))) class ColumnCollection(util.OrderedProperties): """An ordered dictionary that stores a list of ColumnElement instances. Overrides the ``__eq__()`` method to produce SQL clauses between sets of correlated columns. """ def __init__(self, *cols): super(ColumnCollection, self).__init__() self.update((c.key, c) for c in cols) def __str__(self): return repr([str(c) for c in self]) def replace(self, column): """add the given column to this collection, removing unaliased versions of this column as well as existing columns with the same key. e.g.:: t = Table('sometable', metadata, Column('col1', Integer)) t.columns.replace(Column('col1', Integer, key='columnone')) will remove the original 'col1' from the collection, and add the new column under the name 'columnname'. Used by schema.Column to override columns during table reflection. """ if column.name in self and column.key != column.name: other = self[column.name] if other.name == other.key: del self[other.name] util.OrderedProperties.__setitem__(self, column.key, column) def add(self, column): """Add a column to this collection. The key attribute of the column will be used as the hash key for this dictionary. """ self[column.key] = column def __setitem__(self, key, value): if key in self: # this warning is primarily to catch select() statements which # have conflicting column names in their exported columns collection existing = self[key] if not existing.shares_lineage(value): util.warn(("Column %r on table %r being replaced by another " "column with the same key. Consider use_labels " "for select() statements.") % (key, getattr(existing, 'table', None))) util.OrderedProperties.__setitem__(self, key, value) def remove(self, column): del self[column.key] def extend(self, iter): for c in iter: self.add(c) __hash__ = None def __eq__(self, other): l = [] for c in other: for local in self: if c.shares_lineage(local): l.append(c==local) return and_(*l) def __contains__(self, other): if not isinstance(other, basestring): raise exc.ArgumentError("__contains__ requires a string argument") return util.OrderedProperties.__contains__(self, other) def contains_column(self, col): # have to use a Set here, because it will compare the identity # of the column, not just using "==" for comparison which will always return a # "True" value (i.e. a BinaryClause...) return col in util.column_set(self) class ColumnSet(util.ordered_column_set): def contains_column(self, col): return col in self def extend(self, cols): for col in cols: self.add(col) def __add__(self, other): return list(self) + list(other) def __eq__(self, other): l = [] for c in other: for local in self: if c.shares_lineage(local): l.append(c==local) return and_(*l) def __hash__(self): return hash(tuple(x for x in self)) class Selectable(ClauseElement): """mark a class as being selectable""" __visit_name__ = 'selectable' class FromClause(Selectable): """Represent an element that can be used within the ``FROM`` clause of a ``SELECT`` statement. """ __visit_name__ = 'fromclause' named_with_column = False _hide_froms = [] quote = None schema = None def count(self, whereclause=None, **params): """return a SELECT COUNT generated against this :class:`FromClause`.""" if self.primary_key: col = list(self.primary_key)[0] else: col = list(self.columns)[0] return select( [func.count(col).label('tbl_row_count')], whereclause, from_obj=[self], **params) def select(self, whereclause=None, **params): """return a SELECT of this :class:`FromClause`.""" return select([self], whereclause, **params) def join(self, right, onclause=None, isouter=False): """return a join of this :class:`FromClause` against another :class:`FromClause`.""" return Join(self, right, onclause, isouter) def outerjoin(self, right, onclause=None): """return an outer join of this :class:`FromClause` against another :class:`FromClause`.""" return Join(self, right, onclause, True) def alias(self, name=None): """return an alias of this :class:`FromClause`. For table objects, this has the effect of the table being rendered as ``tablename AS aliasname`` in a SELECT statement. For select objects, the effect is that of creating a named subquery, i.e. ``(select ...) AS aliasname``. The :func:`alias()` method is the general way to create a "subquery" out of an existing SELECT. The ``name`` parameter is optional, and if left blank an "anonymous" name will be generated at compile time, guaranteed to be unique against other anonymous constructs used in the same statement. """ return Alias(self, name) def is_derived_from(self, fromclause): """Return True if this FromClause is 'derived' from the given FromClause. An example would be an Alias of a Table is derived from that Table. """ return fromclause in self._cloned_set def replace_selectable(self, old, alias): """replace all occurences of FromClause 'old' with the given Alias object, returning a copy of this :class:`FromClause`. """ global ClauseAdapter if ClauseAdapter is None: from sqlalchemy.sql.util import ClauseAdapter return ClauseAdapter(alias).traverse(self) def correspond_on_equivalents(self, column, equivalents): """Return corresponding_column for the given column, or if None search for a match in the given dictionary. """ col = self.corresponding_column(column, require_embedded=True) if col is None and col in equivalents: for equiv in equivalents[col]: nc = self.corresponding_column(equiv, require_embedded=True) if nc: return nc return col def corresponding_column(self, column, require_embedded=False): """Given a :class:`ColumnElement`, return the exported :class:`ColumnElement` object from this :class:`Selectable` which corresponds to that original :class:`~sqlalchemy.schema.Column` via a common anscestor column. :param column: the target :class:`ColumnElement` to be matched :param require_embedded: only return corresponding columns for the given :class:`ColumnElement`, if the given :class:`ColumnElement` is actually present within a sub-element of this :class:`FromClause`. Normally the column will match if it merely shares a common anscestor with one of the exported columns of this :class:`FromClause`. """ # dont dig around if the column is locally present if self.c.contains_column(column): return column col, intersect = None, None target_set = column.proxy_set cols = self.c for c in cols: i = target_set.intersection(itertools.chain(*[p._cloned_set for p in c.proxy_set])) if i and \ (not require_embedded or c.proxy_set.issuperset(target_set)): if col is None: # no corresponding column yet, pick this one. col, intersect = c, i elif len(i) > len(intersect): # 'c' has a larger field of correspondence than 'col'. # i.e. selectable.c.a1_x->a1.c.x->table.c.x matches # a1.c.x->table.c.x better than # selectable.c.x->table.c.x does. col, intersect = c, i elif i == intersect: # they have the same field of correspondence. # see which proxy_set has fewer columns in it, which indicates # a closer relationship with the root column. Also take into # account the "weight" attribute which CompoundSelect() uses to # give higher precedence to columns based on vertical position # in the compound statement, and discard columns that have no # reference to the target column (also occurs with # CompoundSelect) col_distance = util.reduce(operator.add, [sc._annotations.get('weight', 1) for sc in col.proxy_set if sc.shares_lineage(column)] ) c_distance = util.reduce(operator.add, [sc._annotations.get('weight', 1) for sc in c.proxy_set if sc.shares_lineage(column)] ) if c_distance < col_distance: col, intersect = c, i return col @property def description(self): """a brief description of this FromClause. Used primarily for error message formatting. """ return getattr(self, 'name', self.__class__.__name__ + " object") def _reset_exported(self): """delete memoized collections when a FromClause is cloned.""" for attr in ('_columns', '_primary_key' '_foreign_keys', 'locate_all_froms'): self.__dict__.pop(attr, None) @util.memoized_property def _columns(self): """Return the collection of Column objects contained by this FromClause.""" self._export_columns() return self._columns @util.memoized_property def _primary_key(self): """Return the collection of Column objects which comprise the primary key of this FromClause.""" self._export_columns() return self._primary_key @util.memoized_property def _foreign_keys(self): """Return the collection of ForeignKey objects which this FromClause references.""" self._export_columns() return self._foreign_keys columns = property(attrgetter('_columns'), doc=_columns.__doc__) primary_key = property( attrgetter('_primary_key'), doc=_primary_key.__doc__) foreign_keys = property( attrgetter('_foreign_keys'), doc=_foreign_keys.__doc__) # synonyms for 'columns' c = _select_iterable = property(attrgetter('columns'), doc=_columns.__doc__) def _export_columns(self): """Initialize column collections.""" self._columns = ColumnCollection() self._primary_key = ColumnSet() self._foreign_keys = set() self._populate_column_collection() def _populate_column_collection(self): pass class _BindParamClause(ColumnElement): """Represent a bind parameter. Public constructor is the :func:`bindparam()` function. """ __visit_name__ = 'bindparam' quote = None def __init__(self, key, value, type_=None, unique=False, isoutparam=False, required=False, _compared_to_operator=None, _compared_to_type=None): """Construct a _BindParamClause. key the key for this bind param. Will be used in the generated SQL statement for dialects that use named parameters. This value may be modified when part of a compilation operation, if other :class:`_BindParamClause` objects exist with the same key, or if its length is too long and truncation is required. value Initial value for this bind param. This value may be overridden by the dictionary of parameters sent to statement compilation/execution. type\_ A ``TypeEngine`` object that will be used to pre-process the value corresponding to this :class:`_BindParamClause` at execution time. unique if True, the key name of this BindParamClause will be modified if another :class:`_BindParamClause` of the same name already has been located within the containing :class:`ClauseElement`. required a value is required at execution time. isoutparam if True, the parameter should be treated like a stored procedure "OUT" parameter. """ if unique: self.key = _generated_label("%%(%d %s)s" % (id(self), key or 'param')) else: self.key = key or _generated_label("%%(%d param)s" % id(self)) self._orig_key = key or 'param' self.unique = unique self.value = value self.isoutparam = isoutparam self.required = required if type_ is None: if _compared_to_type is not None: self.type = _compared_to_type._coerce_compared_value(_compared_to_operator, value) else: self.type = sqltypes.type_map.get(type(value), sqltypes.NULLTYPE) elif isinstance(type_, type): self.type = type_() else: self.type = type_ def _clone(self): c = ClauseElement._clone(self) if self.unique: c.key = _generated_label("%%(%d %s)s" % (id(c), c._orig_key or 'param')) return c def _convert_to_unique(self): if not self.unique: self.unique = True self.key = _generated_label("%%(%d %s)s" % (id(self), self._orig_key or 'param')) def bind_processor(self, dialect): return self.type.dialect_impl(dialect).bind_processor(dialect) def compare(self, other, **kw): """Compare this :class:`_BindParamClause` to the given clause.""" return isinstance(other, _BindParamClause) and \ self.type._compare_type_affinity(other.type) and \ self.value == other.value def __getstate__(self): """execute a deferred value for serialization purposes.""" d = self.__dict__.copy() v = self.value if util.callable(v): v = v() d['value'] = v return d def __repr__(self): return "_BindParamClause(%r, %r, type_=%r)" % ( self.key, self.value, self.type ) class _TypeClause(ClauseElement): """Handle a type keyword in a SQL statement. Used by the ``Case`` statement. """ __visit_name__ = 'typeclause' def __init__(self, type): self.type = type class _Generative(object): """Allow a ClauseElement to generate itself via the @_generative decorator. """ def _generate(self): s = self.__class__.__new__(self.__class__) s.__dict__ = self.__dict__.copy() return s class Executable(_Generative): """Mark a ClauseElement as supporting execution. :class:`Executable` is a superclass for all "statement" types of objects, including :func:`select`, :func:`delete`, :func:`update`, :func:`insert`, :func:`text`. """ supports_execution = True _execution_options = util.frozendict() @_generative def execution_options(self, **kw): """ Set non-SQL options for the statement which take effect during execution. Current options include: * autocommit - when True, a COMMIT will be invoked after execution when executed in 'autocommit' mode, i.e. when an explicit transaction is not begun on the connection. Note that DBAPI connections by default are always in a transaction - SQLAlchemy uses rules applied to different kinds of statements to determine if COMMIT will be invoked in order to provide its "autocommit" feature. Typically, all INSERT/UPDATE/DELETE statements as well as CREATE/DROP statements have autocommit behavior enabled; SELECT constructs do not. Use this option when invokving a SELECT or other specific SQL construct where COMMIT is desired (typically when calling stored procedures and such). * stream_results - indicate to the dialect that results should be "streamed" and not pre-buffered, if possible. This is a limitation of many DBAPIs. The flag is currently understood only by the psycopg2 dialect. See also: :meth:`sqlalchemy.engine.base.Connection.execution_options()` :meth:`sqlalchemy.orm.query.Query.execution_options()` """ self._execution_options = self._execution_options.union(kw) # legacy, some outside users may be calling this _Executable = Executable class _TextClause(Executable, ClauseElement): """Represent a literal SQL text fragment. Public constructor is the :func:`text()` function. """ __visit_name__ = 'textclause' _bind_params_regex = re.compile(r'(? RIGHT``.""" __visit_name__ = 'binary' def __init__(self, left, right, operator, type_=None, negate=None, modifiers=None): self.left = _literal_as_text(left).self_group(against=operator) self.right = _literal_as_text(right).self_group(against=operator) self.operator = operator self.type = sqltypes.to_instance(type_) self.negate = negate if modifiers is None: self.modifiers = {} else: self.modifiers = modifiers def __nonzero__(self): try: return self.operator(hash(self.left), hash(self.right)) except: raise TypeError("Boolean value of this clause is not defined") @property def _from_objects(self): return self.left._from_objects + self.right._from_objects def _copy_internals(self, clone=_clone): self.left = clone(self.left) self.right = clone(self.right) def get_children(self, **kwargs): return self.left, self.right def compare(self, other, **kw): """Compare this :class:`_BinaryExpression` against the given :class:`_BinaryExpression`.""" return ( isinstance(other, _BinaryExpression) and self.operator == other.operator and ( self.left.compare(other.left, **kw) and self.right.compare(other.right, **kw) or ( operators.is_commutative(self.operator) and self.left.compare(other.right, **kw) and self.right.compare(other.left, **kw) ) ) ) def self_group(self, against=None): # use small/large defaults for comparison so that unknown # operators are always parenthesized if self.operator is not against and operators.is_precedent(self.operator, against): return _Grouping(self) else: return self def _negate(self): if self.negate is not None: return _BinaryExpression( self.left, self.right, self.negate, negate=self.operator, type_=sqltypes.BOOLEANTYPE, modifiers=self.modifiers) else: return super(_BinaryExpression, self)._negate() class _Exists(_UnaryExpression): __visit_name__ = _UnaryExpression.__visit_name__ _from_objects = [] def __init__(self, *args, **kwargs): if args and isinstance(args[0], (_SelectBaseMixin, _ScalarSelect)): s = args[0] else: if not args: args = ([literal_column('*')],) s = select(*args, **kwargs).as_scalar().self_group() _UnaryExpression.__init__(self, s, operator=operators.exists, type_=sqltypes.Boolean) def select(self, whereclause=None, **params): return select([self], whereclause, **params) def correlate(self, fromclause): e = self._clone() e.element = self.element.correlate(fromclause).self_group() return e def select_from(self, clause): """return a new exists() construct with the given expression set as its FROM clause. """ e = self._clone() e.element = self.element.select_from(clause).self_group() return e def where(self, clause): """return a new exists() construct with the given expression added to its WHERE clause, joined to the existing clause via AND, if any. """ e = self._clone() e.element = self.element.where(clause).self_group() return e class Join(FromClause): """represent a ``JOIN`` construct between two :class:`FromClause` elements. The public constructor function for :class:`Join` is the module-level :func:`join()` function, as well as the :func:`join()` method available off all :class:`FromClause` subclasses. """ __visit_name__ = 'join' def __init__(self, left, right, onclause=None, isouter=False): self.left = _literal_as_text(left) self.right = _literal_as_text(right).self_group() if onclause is None: self.onclause = self._match_primaries(self.left, self.right) else: self.onclause = onclause self.isouter = isouter self.__folded_equivalents = None @property def description(self): return "Join object on %s(%d) and %s(%d)" % ( self.left.description, id(self.left), self.right.description, id(self.right)) def is_derived_from(self, fromclause): return fromclause is self or \ self.left.is_derived_from(fromclause) or\ self.right.is_derived_from(fromclause) def self_group(self, against=None): return _FromGrouping(self) def _populate_column_collection(self): columns = [c for c in self.left.columns] + [c for c in self.right.columns] global sql_util if not sql_util: from sqlalchemy.sql import util as sql_util self._primary_key.extend(sql_util.reduce_columns( (c for c in columns if c.primary_key), self.onclause)) self._columns.update((col._label, col) for col in columns) self._foreign_keys.update(itertools.chain(*[col.foreign_keys for col in columns])) def _copy_internals(self, clone=_clone): self._reset_exported() self.left = clone(self.left) self.right = clone(self.right) self.onclause = clone(self.onclause) self.__folded_equivalents = None def get_children(self, **kwargs): return self.left, self.right, self.onclause def _match_primaries(self, left, right): global sql_util if not sql_util: from sqlalchemy.sql import util as sql_util if isinstance(left, Join): left_right = left.right else: left_right = None return sql_util.join_condition(left, right, a_subset=left_right) def select(self, whereclause=None, fold_equivalents=False, **kwargs): """Create a :class:`Select` from this :class:`Join`. :param whereclause: the WHERE criterion that will be sent to the :func:`select()` function :param fold_equivalents: based on the join criterion of this :class:`Join`, do not include repeat column names in the column list of the resulting select, for columns that are calculated to be "equivalent" based on the join criterion of this :class:`Join`. This will recursively apply to any joins directly nested by this one as well. This flag is specific to a particular use case by the ORM and is deprecated as of 0.6. :param \**kwargs: all other kwargs are sent to the underlying :func:`select()` function. """ if fold_equivalents: global sql_util if not sql_util: from sqlalchemy.sql import util as sql_util util.warn_deprecated("fold_equivalents is deprecated.") collist = sql_util.folded_equivalents(self) else: collist = [self.left, self.right] return select(collist, whereclause, from_obj=[self], **kwargs) @property def bind(self): return self.left.bind or self.right.bind def alias(self, name=None): """Create a :class:`Select` out of this :class:`Join` clause and return an :class:`Alias` of it. The :class:`Select` is not correlating. """ return self.select(use_labels=True, correlate=False).alias(name) @property def _hide_froms(self): return itertools.chain(*[_from_objects(x.left, x.right) for x in self._cloned_set]) @property def _from_objects(self): return [self] + \ self.onclause._from_objects + \ self.left._from_objects + \ self.right._from_objects class Alias(FromClause): """Represents an table or selectable alias (AS). Represents an alias, as typically applied to any table or sub-select within a SQL statement using the ``AS`` keyword (or without the keyword on certain databases such as Oracle). This object is constructed from the :func:`alias()` module level function as well as the :func:`alias()` method available on all :class:`FromClause` subclasses. """ __visit_name__ = 'alias' named_with_column = True def __init__(self, selectable, alias=None): baseselectable = selectable while isinstance(baseselectable, Alias): baseselectable = baseselectable.element self.original = baseselectable self.supports_execution = baseselectable.supports_execution if self.supports_execution: self._execution_options = baseselectable._execution_options self.element = selectable if alias is None: if self.original.named_with_column: alias = getattr(self.original, 'name', None) alias = _generated_label('%%(%d %s)s' % (id(self), alias or 'anon')) self.name = alias @property def description(self): # Py3K #return self.name # Py2K return self.name.encode('ascii', 'backslashreplace') # end Py2K def as_scalar(self): try: return self.element.as_scalar() except AttributeError: raise AttributeError("Element %s does not support 'as_scalar()'" % self.element) def is_derived_from(self, fromclause): if fromclause in self._cloned_set: return True return self.element.is_derived_from(fromclause) def _populate_column_collection(self): for col in self.element.columns: col._make_proxy(self) def _copy_internals(self, clone=_clone): self._reset_exported() self.element = _clone(self.element) baseselectable = self.element while isinstance(baseselectable, Alias): baseselectable = baseselectable.element self.original = baseselectable def get_children(self, column_collections=True, aliased_selectables=True, **kwargs): if column_collections: for c in self.c: yield c if aliased_selectables: yield self.element @property def _from_objects(self): return [self] @property def bind(self): return self.element.bind class _Grouping(ColumnElement): """Represent a grouping within a column expression""" __visit_name__ = 'grouping' def __init__(self, element): self.element = element self.type = getattr(element, 'type', None) @property def _label(self): return getattr(self.element, '_label', None) or self.anon_label def _copy_internals(self, clone=_clone): self.element = clone(self.element) def get_children(self, **kwargs): return self.element, @property def _from_objects(self): return self.element._from_objects def __getattr__(self, attr): return getattr(self.element, attr) def __getstate__(self): return {'element':self.element, 'type':self.type} def __setstate__(self, state): self.element = state['element'] self.type = state['type'] class _FromGrouping(FromClause): """Represent a grouping of a FROM clause""" __visit_name__ = 'grouping' def __init__(self, element): self.element = element @property def columns(self): return self.element.columns @property def _hide_froms(self): return self.element._hide_froms def get_children(self, **kwargs): return self.element, def _copy_internals(self, clone=_clone): self.element = clone(self.element) @property def _from_objects(self): return self.element._from_objects def __getattr__(self, attr): return getattr(self.element, attr) def __getstate__(self): return {'element':self.element} def __setstate__(self, state): self.element = state['element'] class _Label(ColumnElement): """Represents a column label (AS). Represent a label, as typically applied to any column-level element using the ``AS`` sql keyword. This object is constructed from the :func:`label()` module level function as well as the :func:`label()` method available on all :class:`ColumnElement` subclasses. """ __visit_name__ = 'label' def __init__(self, name, element, type_=None): while isinstance(element, _Label): element = element.element self.name = self.key = self._label = name or \ _generated_label("%%(%d %s)s" % ( id(self), getattr(element, 'name', 'anon')) ) self._element = element self._type = type_ self.quote = element.quote @util.memoized_property def type(self): return sqltypes.to_instance( self._type or getattr(self._element, 'type', None) ) @util.memoized_property def element(self): return self._element.self_group(against=operators.as_) def _proxy_attr(name): get = attrgetter(name) def attr(self): return get(self.element) return property(attr) proxies = _proxy_attr('proxies') base_columns = _proxy_attr('base_columns') proxy_set = _proxy_attr('proxy_set') primary_key = _proxy_attr('primary_key') foreign_keys = _proxy_attr('foreign_keys') def get_children(self, **kwargs): return self.element, def _copy_internals(self, clone=_clone): self.element = clone(self.element) @property def _from_objects(self): return self.element._from_objects def _make_proxy(self, selectable, name = None): if isinstance(self.element, (Selectable, ColumnElement)): e = self.element._make_proxy(selectable, name=self.name) else: e = column(self.name)._make_proxy(selectable=selectable) e.proxies.append(self) return e class ColumnClause(_Immutable, ColumnElement): """Represents a generic column expression from any textual string. This includes columns associated with tables, aliases and select statements, but also any arbitrary text. May or may not be bound to an underlying :class:`Selectable`. :class:`ColumnClause` is usually created publically via the :func:`column()` function or the :func:`literal_column()` function. text the text of the element. selectable parent selectable. type ``TypeEngine`` object which can associate this :class:`ColumnClause` with a type. is_literal if True, the :class:`ColumnClause` is assumed to be an exact expression that will be delivered to the output with no quoting rules applied regardless of case sensitive settings. the :func:`literal_column()` function is usually used to create such a :class:`ColumnClause`. """ __visit_name__ = 'column' onupdate = default = server_default = server_onupdate = None def __init__(self, text, selectable=None, type_=None, is_literal=False): self.key = self.name = text self.table = selectable self.type = sqltypes.to_instance(type_) self.is_literal = is_literal @util.memoized_property def description(self): # Py3K #return self.name # Py2K return self.name.encode('ascii', 'backslashreplace') # end Py2K @util.memoized_property def _label(self): if self.is_literal: return None elif self.table is not None and self.table.named_with_column: if getattr(self.table, 'schema', None): label = self.table.schema.replace('.', '_') + "_" + \ _escape_for_generated(self.table.name) + "_" + \ _escape_for_generated(self.name) else: label = _escape_for_generated(self.table.name) + "_" + \ _escape_for_generated(self.name) return _generated_label(label) else: return self.name def label(self, name): if name is None: return self else: return super(ColumnClause, self).label(name) @property def _from_objects(self): if self.table is not None: return [self.table] else: return [] def _bind_param(self, operator, obj): return _BindParamClause(self.name, obj, _compared_to_operator=operator, _compared_to_type=self.type, unique=True) def _make_proxy(self, selectable, name=None, attach=True): # propagate the "is_literal" flag only if we are keeping our name, # otherwise its considered to be a label is_literal = self.is_literal and (name is None or name == self.name) c = ColumnClause( name or self.name, selectable=selectable, type_=self.type, is_literal=is_literal ) c.proxies = [self] if attach: selectable.columns[c.name] = c return c class TableClause(_Immutable, FromClause): """Represents a "table" construct. Note that this represents tables only as another syntactical construct within SQL expressions; it does not provide schema-level functionality. """ __visit_name__ = 'table' named_with_column = True def __init__(self, name, *columns): super(TableClause, self).__init__() self.name = self.fullname = name self._columns = ColumnCollection() self._primary_key = ColumnSet() self._foreign_keys = set() for c in columns: self.append_column(c) def _export_columns(self): raise NotImplementedError() @util.memoized_property def description(self): # Py3K #return self.name # Py2K return self.name.encode('ascii', 'backslashreplace') # end Py2K def append_column(self, c): self._columns[c.name] = c c.table = self def get_children(self, column_collections=True, **kwargs): if column_collections: return [c for c in self.c] else: return [] def count(self, whereclause=None, **params): """return a SELECT COUNT generated against this :class:`TableClause`.""" if self.primary_key: col = list(self.primary_key)[0] else: col = list(self.columns)[0] return select( [func.count(col).label('tbl_row_count')], whereclause, from_obj=[self], **params) def insert(self, values=None, inline=False, **kwargs): """Generate an :func:`insert()` construct.""" return insert(self, values=values, inline=inline, **kwargs) def update(self, whereclause=None, values=None, inline=False, **kwargs): """Generate an :func:`update()` construct.""" return update(self, whereclause=whereclause, values=values, inline=inline, **kwargs) def delete(self, whereclause=None, **kwargs): """Generate a :func:`delete()` construct.""" return delete(self, whereclause, **kwargs) @property def _from_objects(self): return [self] class _SelectBaseMixin(Executable): """Base class for :class:`Select` and ``CompoundSelects``.""" def __init__(self, use_labels=False, for_update=False, limit=None, offset=None, order_by=None, group_by=None, bind=None, autocommit=None): self.use_labels = use_labels self.for_update = for_update if autocommit is not None: util.warn_deprecated("autocommit on select() is deprecated. " "Use .execution_options(autocommit=True)") self._execution_options = self._execution_options.union({'autocommit':autocommit}) self._limit = limit self._offset = offset self._bind = bind self._order_by_clause = ClauseList(*util.to_list(order_by) or []) self._group_by_clause = ClauseList(*util.to_list(group_by) or []) def as_scalar(self): """return a 'scalar' representation of this selectable, which can be used as a column expression. Typically, a select statement which has only one column in its columns clause is eligible to be used as a scalar expression. The returned object is an instance of :class:`_ScalarSelect`. """ return _ScalarSelect(self) @_generative def apply_labels(self): """return a new selectable with the 'use_labels' flag set to True. This will result in column expressions being generated using labels against their table name, such as "SELECT somecolumn AS tablename_somecolumn". This allows selectables which contain multiple FROM clauses to produce a unique set of column names regardless of name conflicts among the individual FROM clauses. """ self.use_labels = True def label(self, name): """return a 'scalar' representation of this selectable, embedded as a subquery with a label. See also ``as_scalar()``. """ return self.as_scalar().label(name) @_generative @util.deprecated(message="autocommit() is deprecated. " "Use .execution_options(autocommit=True)") def autocommit(self): """return a new selectable with the 'autocommit' flag set to True.""" self._execution_options = self._execution_options.union({'autocommit':True}) def _generate(self): """Override the default _generate() method to also clear out exported collections.""" s = self.__class__.__new__(self.__class__) s.__dict__ = self.__dict__.copy() s._reset_exported() return s @_generative def limit(self, limit): """return a new selectable with the given LIMIT criterion applied.""" self._limit = limit @_generative def offset(self, offset): """return a new selectable with the given OFFSET criterion applied.""" self._offset = offset @_generative def order_by(self, *clauses): """return a new selectable with the given list of ORDER BY criterion applied. The criterion will be appended to any pre-existing ORDER BY criterion. """ self.append_order_by(*clauses) @_generative def group_by(self, *clauses): """return a new selectable with the given list of GROUP BY criterion applied. The criterion will be appended to any pre-existing GROUP BY criterion. """ self.append_group_by(*clauses) def append_order_by(self, *clauses): """Append the given ORDER BY criterion applied to this selectable. The criterion will be appended to any pre-existing ORDER BY criterion. """ if len(clauses) == 1 and clauses[0] is None: self._order_by_clause = ClauseList() else: if getattr(self, '_order_by_clause', None) is not None: clauses = list(self._order_by_clause) + list(clauses) self._order_by_clause = ClauseList(*clauses) def append_group_by(self, *clauses): """Append the given GROUP BY criterion applied to this selectable. The criterion will be appended to any pre-existing GROUP BY criterion. """ if len(clauses) == 1 and clauses[0] is None: self._group_by_clause = ClauseList() else: if getattr(self, '_group_by_clause', None) is not None: clauses = list(self._group_by_clause) + list(clauses) self._group_by_clause = ClauseList(*clauses) @property def _from_objects(self): return [self] class _ScalarSelect(_Grouping): _from_objects = [] def __init__(self, element): self.element = element cols = list(element.c) self.type = cols[0].type @property def columns(self): raise exc.InvalidRequestError("Scalar Select expression has no columns; " "use this object directly within a column-level expression.") c = columns def self_group(self, **kwargs): return self def _make_proxy(self, selectable, name): return list(self.inner_columns)[0]._make_proxy(selectable, name) class CompoundSelect(_SelectBaseMixin, FromClause): """Forms the basis of ``UNION``, ``UNION ALL``, and other SELECT-based set operations.""" __visit_name__ = 'compound_select' UNION = util.symbol('UNION') UNION_ALL = util.symbol('UNION ALL') EXCEPT = util.symbol('EXCEPT') EXCEPT_ALL = util.symbol('EXCEPT ALL') INTERSECT = util.symbol('INTERSECT') INTERSECT_ALL = util.symbol('INTERSECT ALL') def __init__(self, keyword, *selects, **kwargs): self._should_correlate = kwargs.pop('correlate', False) self.keyword = keyword self.selects = [] numcols = None # some DBs do not like ORDER BY in the inner queries of a UNION, etc. for n, s in enumerate(selects): s = _clause_element_as_expr(s) if not numcols: numcols = len(s.c) elif len(s.c) != numcols: raise exc.ArgumentError( "All selectables passed to CompoundSelect must " "have identical numbers of columns; select #%d has %d columns," " select #%d has %d" % (1, len(self.selects[0].c), n+1, len(s.c)) ) self.selects.append(s.self_group(self)) _SelectBaseMixin.__init__(self, **kwargs) def self_group(self, against=None): return _FromGrouping(self) def is_derived_from(self, fromclause): for s in self.selects: if s.is_derived_from(fromclause): return True return False def _populate_column_collection(self): for cols in zip(*[s.c for s in self.selects]): # this is a slightly hacky thing - the union exports a column that # resembles just that of the *first* selectable. to get at a "composite" column, # particularly foreign keys, you have to dig through the proxies collection # which we generate below. We may want to improve upon this, # such as perhaps _make_proxy can accept a list of other columns that # are "shared" - schema.column can then copy all the ForeignKeys in. # this would allow the union() to have all those fks too. proxy = cols[0]._make_proxy( self, name=self.use_labels and cols[0]._label or None) # hand-construct the "proxies" collection to include all derived columns # place a 'weight' annotation corresponding to how low in the list of # select()s the column occurs, so that the corresponding_column() operation # can resolve conflicts proxy.proxies = [c._annotate({'weight':i + 1}) for i, c in enumerate(cols)] def _copy_internals(self, clone=_clone): self._reset_exported() self.selects = [clone(s) for s in self.selects] if hasattr(self, '_col_map'): del self._col_map for attr in ('_order_by_clause', '_group_by_clause'): if getattr(self, attr) is not None: setattr(self, attr, clone(getattr(self, attr))) def get_children(self, column_collections=True, **kwargs): return (column_collections and list(self.c) or []) + \ [self._order_by_clause, self._group_by_clause] + list(self.selects) def bind(self): if self._bind: return self._bind for s in self.selects: e = s.bind if e: return e else: return None def _set_bind(self, bind): self._bind = bind bind = property(bind, _set_bind) class Select(_SelectBaseMixin, FromClause): """Represents a ``SELECT`` statement. Select statements support appendable clauses, as well as the ability to execute themselves and return a result set. """ __visit_name__ = 'select' _prefixes = () _hints = util.frozendict() def __init__(self, columns, whereclause=None, from_obj=None, distinct=False, having=None, correlate=True, prefixes=None, **kwargs): """Construct a Select object. The public constructor for Select is the :func:`select` function; see that function for argument descriptions. Additional generative and mutator methods are available on the :class:`_SelectBaseMixin` superclass. """ self._should_correlate = correlate self._distinct = distinct self._correlate = set() self._froms = util.OrderedSet() try: cols_present = bool(columns) except TypeError: raise exc.ArgumentError("columns argument to select() must " "be a Python list or other iterable") if cols_present: self._raw_columns = [] for c in columns: c = _literal_as_column(c) if isinstance(c, _ScalarSelect): c = c.self_group(against=operators.comma_op) self._raw_columns.append(c) self._froms.update(_from_objects(*self._raw_columns)) else: self._raw_columns = [] if whereclause is not None: self._whereclause = _literal_as_text(whereclause) self._froms.update(_from_objects(self._whereclause)) else: self._whereclause = None if from_obj is not None: for f in util.to_list(from_obj): if _is_literal(f): self._froms.add(_TextClause(f)) else: self._froms.add(f) if having is not None: self._having = _literal_as_text(having) else: self._having = None if prefixes: self._prefixes = tuple([_literal_as_text(p) for p in prefixes]) _SelectBaseMixin.__init__(self, **kwargs) def _get_display_froms(self, existing_froms=None): """Return the full list of 'from' clauses to be displayed. Takes into account a set of existing froms which may be rendered in the FROM clause of enclosing selects; this Select may want to leave those absent if it is automatically correlating. """ froms = self._froms toremove = itertools.chain(*[f._hide_froms for f in froms]) if toremove: froms = froms.difference(toremove) if len(froms) > 1 or self._correlate: if self._correlate: froms = froms.difference(_cloned_intersection(froms, self._correlate)) if self._should_correlate and existing_froms: froms = froms.difference(_cloned_intersection(froms, existing_froms)) if not len(froms): raise exc.InvalidRequestError( "Select statement '%s' returned no FROM clauses " "due to auto-correlation; specify correlate() " "to control correlation manually." % self) return froms @property def froms(self): """Return the displayed list of FromClause elements.""" return self._get_display_froms() @_generative def with_hint(self, selectable, text, dialect_name=None): """Add an indexing hint for the given selectable to this :class:`Select`. The text of the hint is written specific to a specific backend, and typically uses Python string substitution syntax to render the name of the table or alias, such as for Oracle:: select([mytable]).with_hint(mytable, "+ index(%(name)s ix_mytable)") Would render SQL as:: select /*+ index(mytable ix_mytable) */ ... from mytable The ``dialect_name`` option will limit the rendering of a particular hint to a particular backend. Such as, to add hints for both Oracle and Sybase simultaneously:: select([mytable]).\ with_hint(mytable, "+ index(%(name)s ix_mytable)", 'oracle').\ with_hint(mytable, "WITH INDEX ix_mytable", 'sybase') """ if not dialect_name: dialect_name = '*' self._hints = self._hints.union({(selectable, dialect_name):text}) @property def type(self): raise exc.InvalidRequestError("Select objects don't have a type. " "Call as_scalar() on this Select object " "to return a 'scalar' version of this Select.") @util.memoized_instancemethod def locate_all_froms(self): """return a Set of all FromClause elements referenced by this Select. This set is a superset of that returned by the ``froms`` property, which is specifically for those FromClause elements that would actually be rendered. """ return self._froms.union(_from_objects(*list(self._froms))) @property def inner_columns(self): """an iterator of all ColumnElement expressions which would be rendered into the columns clause of the resulting SELECT statement. """ return _select_iterables(self._raw_columns) def is_derived_from(self, fromclause): if self in fromclause._cloned_set: return True for f in self.locate_all_froms(): if f.is_derived_from(fromclause): return True return False def _copy_internals(self, clone=_clone): self._reset_exported() from_cloned = dict((f, clone(f)) for f in self._froms.union(self._correlate)) self._froms = util.OrderedSet(from_cloned[f] for f in self._froms) self._correlate = set(from_cloned[f] for f in self._correlate) self._raw_columns = [clone(c) for c in self._raw_columns] for attr in ('_whereclause', '_having', '_order_by_clause', '_group_by_clause'): if getattr(self, attr) is not None: setattr(self, attr, clone(getattr(self, attr))) def get_children(self, column_collections=True, **kwargs): """return child elements as per the ClauseElement specification.""" return (column_collections and list(self.columns) or []) + \ self._raw_columns + list(self._froms) + \ [x for x in (self._whereclause, self._having, self._order_by_clause, self._group_by_clause) if x is not None] @_generative def column(self, column): """return a new select() construct with the given column expression added to its columns clause. """ column = _literal_as_column(column) if isinstance(column, _ScalarSelect): column = column.self_group(against=operators.comma_op) self._raw_columns = self._raw_columns + [column] self._froms = self._froms.union(_from_objects(column)) @_generative def with_only_columns(self, columns): """return a new select() construct with its columns clause replaced with the given columns. """ self._raw_columns = [ isinstance(c, _ScalarSelect) and c.self_group(against=operators.comma_op) or c for c in [_literal_as_column(c) for c in columns] ] @_generative def where(self, whereclause): """return a new select() construct with the given expression added to its WHERE clause, joined to the existing clause via AND, if any. """ self.append_whereclause(whereclause) @_generative def having(self, having): """return a new select() construct with the given expression added to its HAVING clause, joined to the existing clause via AND, if any. """ self.append_having(having) @_generative def distinct(self): """return a new select() construct which will apply DISTINCT to its columns clause. """ self._distinct = True @_generative def prefix_with(self, clause): """return a new select() construct which will apply the given expression to the start of its columns clause, not using any commas. """ clause = _literal_as_text(clause) self._prefixes = self._prefixes + (clause,) @_generative def select_from(self, fromclause): """return a new select() construct with the given FROM expression applied to its list of FROM objects. """ fromclause = _literal_as_text(fromclause) self._froms = self._froms.union([fromclause]) @_generative def correlate(self, *fromclauses): """return a new select() construct which will correlate the given FROM clauses to that of an enclosing select(), if a match is found. By "match", the given fromclause must be present in this select's list of FROM objects and also present in an enclosing select's list of FROM objects. Calling this method turns off the select's default behavior of "auto-correlation". Normally, select() auto-correlates all of its FROM clauses to those of an embedded select when compiled. If the fromclause is None, correlation is disabled for the returned select(). """ self._should_correlate = False if fromclauses == (None,): self._correlate = set() else: self._correlate = self._correlate.union(fromclauses) def append_correlation(self, fromclause): """append the given correlation expression to this select() construct.""" self._should_correlate = False self._correlate = self._correlate.union([fromclause]) def append_column(self, column): """append the given column expression to the columns clause of this select() construct. """ column = _literal_as_column(column) if isinstance(column, _ScalarSelect): column = column.self_group(against=operators.comma_op) self._raw_columns = self._raw_columns + [column] self._froms = self._froms.union(_from_objects(column)) self._reset_exported() def append_prefix(self, clause): """append the given columns clause prefix expression to this select() construct. """ clause = _literal_as_text(clause) self._prefixes = self._prefixes + (clause,) def append_whereclause(self, whereclause): """append the given expression to this select() construct's WHERE criterion. The expression will be joined to existing WHERE criterion via AND. """ whereclause = _literal_as_text(whereclause) self._froms = self._froms.union(_from_objects(whereclause)) if self._whereclause is not None: self._whereclause = and_(self._whereclause, whereclause) else: self._whereclause = whereclause def append_having(self, having): """append the given expression to this select() construct's HAVING criterion. The expression will be joined to existing HAVING criterion via AND. """ if self._having is not None: self._having = and_(self._having, _literal_as_text(having)) else: self._having = _literal_as_text(having) def append_from(self, fromclause): """append the given FromClause expression to this select() construct's FROM clause. """ if _is_literal(fromclause): fromclause = _TextClause(fromclause) self._froms = self._froms.union([fromclause]) def __exportable_columns(self): for column in self._raw_columns: if isinstance(column, Selectable): for co in column.columns: yield co elif isinstance(column, ColumnElement): yield column else: continue def _populate_column_collection(self): for c in self.__exportable_columns(): c._make_proxy(self, name=self.use_labels and c._label or None) def self_group(self, against=None): """return a 'grouping' construct as per the ClauseElement specification. This produces an element that can be embedded in an expression. Note that this method is called automatically as needed when constructing expressions. """ if isinstance(against, CompoundSelect): return self return _FromGrouping(self) def union(self, other, **kwargs): """return a SQL UNION of this select() construct against the given selectable.""" return union(self, other, **kwargs) def union_all(self, other, **kwargs): """return a SQL UNION ALL of this select() construct against the given selectable. """ return union_all(self, other, **kwargs) def except_(self, other, **kwargs): """return a SQL EXCEPT of this select() construct against the given selectable.""" return except_(self, other, **kwargs) def except_all(self, other, **kwargs): """return a SQL EXCEPT ALL of this select() construct against the given selectable. """ return except_all(self, other, **kwargs) def intersect(self, other, **kwargs): """return a SQL INTERSECT of this select() construct against the given selectable. """ return intersect(self, other, **kwargs) def intersect_all(self, other, **kwargs): """return a SQL INTERSECT ALL of this select() construct against the given selectable. """ return intersect_all(self, other, **kwargs) def bind(self): if self._bind: return self._bind if not self._froms: for c in self._raw_columns: e = c.bind if e: self._bind = e return e else: e = list(self._froms)[0].bind if e: self._bind = e return e return None def _set_bind(self, bind): self._bind = bind bind = property(bind, _set_bind) class _UpdateBase(Executable, ClauseElement): """Form the base for ``INSERT``, ``UPDATE``, and ``DELETE`` statements.""" __visit_name__ = 'update_base' _execution_options = Executable._execution_options.union({'autocommit':True}) kwargs = util.frozendict() def _process_colparams(self, parameters): if isinstance(parameters, (list, tuple)): pp = {} for i, c in enumerate(self.table.c): pp[c.key] = parameters[i] return pp else: return parameters def params(self, *arg, **kw): raise NotImplementedError( "params() is not supported for INSERT/UPDATE/DELETE statements." " To set the values for an INSERT or UPDATE statement, use" " stmt.values(**parameters).") def bind(self): return self._bind or self.table.bind def _set_bind(self, bind): self._bind = bind bind = property(bind, _set_bind) _returning_re = re.compile(r'(?:firebird|postgres(?:ql)?)_returning') def _process_deprecated_kw(self, kwargs): for k in list(kwargs): m = self._returning_re.match(k) if m: self._returning = kwargs.pop(k) util.warn_deprecated( "The %r argument is deprecated. Please " "use statement.returning(col1, col2, ...)" % k ) return kwargs @_generative def returning(self, *cols): """Add a RETURNING or equivalent clause to this statement. The given list of columns represent columns within the table that is the target of the INSERT, UPDATE, or DELETE. Each element can be any column expression. :class:`~sqlalchemy.schema.Table` objects will be expanded into their individual columns. Upon compilation, a RETURNING clause, or database equivalent, will be rendered within the statement. For INSERT and UPDATE, the values are the newly inserted/updated values. For DELETE, the values are those of the rows which were deleted. Upon execution, the values of the columns to be returned are made available via the result set and can be iterated using ``fetchone()`` and similar. For DBAPIs which do not natively support returning values (i.e. cx_oracle), SQLAlchemy will approximate this behavior at the result level so that a reasonable amount of behavioral neutrality is provided. Note that not all databases/DBAPIs support RETURNING. For those backends with no support, an exception is raised upon compilation and/or execution. For those who do support it, the functionality across backends varies greatly, including restrictions on executemany() and other statements which return multiple rows. Please read the documentation notes for the database in use in order to determine the availability of RETURNING. """ self._returning = cols class _ValuesBase(_UpdateBase): __visit_name__ = 'values_base' def __init__(self, table, values): self.table = table self.parameters = self._process_colparams(values) @_generative def values(self, *args, **kwargs): """specify the VALUES clause for an INSERT statement, or the SET clause for an UPDATE. \**kwargs key= arguments \*args A single dictionary can be sent as the first positional argument. This allows non-string based keys, such as Column objects, to be used. """ if args: v = args[0] else: v = {} if self.parameters is None: self.parameters = self._process_colparams(v) self.parameters.update(kwargs) else: self.parameters = self.parameters.copy() self.parameters.update(self._process_colparams(v)) self.parameters.update(kwargs) class Insert(_ValuesBase): """Represent an INSERT construct. The :class:`Insert` object is created using the :func:`insert()` function. """ __visit_name__ = 'insert' _prefixes = () def __init__(self, table, values=None, inline=False, bind=None, prefixes=None, returning=None, **kwargs): _ValuesBase.__init__(self, table, values) self._bind = bind self.select = None self.inline = inline self._returning = returning if prefixes: self._prefixes = tuple([_literal_as_text(p) for p in prefixes]) if kwargs: self.kwargs = self._process_deprecated_kw(kwargs) def get_children(self, **kwargs): if self.select is not None: return self.select, else: return () def _copy_internals(self, clone=_clone): # TODO: coverage self.parameters = self.parameters.copy() @_generative def prefix_with(self, clause): """Add a word or expression between INSERT and INTO. Generative. If multiple prefixes are supplied, they will be separated with spaces. """ clause = _literal_as_text(clause) self._prefixes = self._prefixes + (clause,) class Update(_ValuesBase): """Represent an Update construct. The :class:`Update` object is created using the :func:`update()` function. """ __visit_name__ = 'update' def __init__(self, table, whereclause, values=None, inline=False, bind=None, returning=None, **kwargs): _ValuesBase.__init__(self, table, values) self._bind = bind self._returning = returning if whereclause is not None: self._whereclause = _literal_as_text(whereclause) else: self._whereclause = None self.inline = inline if kwargs: self.kwargs = self._process_deprecated_kw(kwargs) def get_children(self, **kwargs): if self._whereclause is not None: return self._whereclause, else: return () def _copy_internals(self, clone=_clone): # TODO: coverage self._whereclause = clone(self._whereclause) self.parameters = self.parameters.copy() @_generative def where(self, whereclause): """return a new update() construct with the given expression added to its WHERE clause, joined to the existing clause via AND, if any. """ if self._whereclause is not None: self._whereclause = and_(self._whereclause, _literal_as_text(whereclause)) else: self._whereclause = _literal_as_text(whereclause) class Delete(_UpdateBase): """Represent a DELETE construct. The :class:`Delete` object is created using the :func:`delete()` function. """ __visit_name__ = 'delete' def __init__(self, table, whereclause, bind=None, returning =None, **kwargs): self._bind = bind self.table = table self._returning = returning if whereclause is not None: self._whereclause = _literal_as_text(whereclause) else: self._whereclause = None if kwargs: self.kwargs = self._process_deprecated_kw(kwargs) def get_children(self, **kwargs): if self._whereclause is not None: return self._whereclause, else: return () @_generative def where(self, whereclause): """Add the given WHERE clause to a newly returned delete construct.""" if self._whereclause is not None: self._whereclause = and_(self._whereclause, _literal_as_text(whereclause)) else: self._whereclause = _literal_as_text(whereclause) def _copy_internals(self, clone=_clone): # TODO: coverage self._whereclause = clone(self._whereclause) class _IdentifiedClause(Executable, ClauseElement): __visit_name__ = 'identified' _execution_options = Executable._execution_options.union({'autocommit':False}) quote = None def __init__(self, ident): self.ident = ident class SavepointClause(_IdentifiedClause): __visit_name__ = 'savepoint' class RollbackToSavepointClause(_IdentifiedClause): __visit_name__ = 'rollback_to_savepoint' class ReleaseSavepointClause(_IdentifiedClause): __visit_name__ = 'release_savepoint'