597 lines
22 KiB
Python
597 lines
22 KiB
Python
# sqlite.py
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# Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010 Michael Bayer mike_mp@zzzcomputing.com
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#
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# This module is part of SQLAlchemy and is released under
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# the MIT License: http://www.opensource.org/licenses/mit-license.php
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"""Support for the SQLite database.
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For information on connecting using a specific driver, see the documentation
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section regarding that driver.
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Date and Time Types
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-------------------
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SQLite does not have built-in DATE, TIME, or DATETIME types, and pysqlite does not provide
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out of the box functionality for translating values between Python `datetime` objects
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and a SQLite-supported format. SQLAlchemy's own :class:`~sqlalchemy.types.DateTime`
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and related types provide date formatting and parsing functionality when SQlite is used.
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The implementation classes are :class:`DATETIME`, :class:`DATE` and :class:`TIME`.
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These types represent dates and times as ISO formatted strings, which also nicely
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support ordering. There's no reliance on typical "libc" internals for these functions
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so historical dates are fully supported.
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Auto Incrementing Behavior
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--------------------------
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Background on SQLite's autoincrement is at: http://sqlite.org/autoinc.html
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Two things to note:
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* The AUTOINCREMENT keyword is **not** required for SQLite tables to
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generate primary key values automatically. AUTOINCREMENT only means that
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the algorithm used to generate ROWID values should be slightly different.
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* SQLite does **not** generate primary key (i.e. ROWID) values, even for
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one column, if the table has a composite (i.e. multi-column) primary key.
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This is regardless of the AUTOINCREMENT keyword being present or not.
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To specifically render the AUTOINCREMENT keyword on the primary key
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column when rendering DDL, add the flag ``sqlite_autoincrement=True``
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to the Table construct::
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Table('sometable', metadata,
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Column('id', Integer, primary_key=True),
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sqlite_autoincrement=True)
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"""
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import datetime, re, time
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from sqlalchemy import schema as sa_schema
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from sqlalchemy import sql, exc, pool, DefaultClause
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from sqlalchemy.engine import default
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from sqlalchemy.engine import reflection
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from sqlalchemy import types as sqltypes
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from sqlalchemy import util
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from sqlalchemy.sql import compiler, functions as sql_functions
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from sqlalchemy.util import NoneType
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from sqlalchemy import processors
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from sqlalchemy.types import BLOB, BOOLEAN, CHAR, DATE, DATETIME, DECIMAL,\
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FLOAT, INTEGER, NUMERIC, SMALLINT, TEXT, TIME,\
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TIMESTAMP, VARCHAR
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class _DateTimeMixin(object):
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_reg = None
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_storage_format = None
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def __init__(self, storage_format=None, regexp=None, **kwargs):
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if regexp is not None:
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self._reg = re.compile(regexp)
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if storage_format is not None:
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self._storage_format = storage_format
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class DATETIME(_DateTimeMixin, sqltypes.DateTime):
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_storage_format = "%04d-%02d-%02d %02d:%02d:%02d.%06d"
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def bind_processor(self, dialect):
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datetime_datetime = datetime.datetime
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datetime_date = datetime.date
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format = self._storage_format
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def process(value):
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if value is None:
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return None
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elif isinstance(value, datetime_datetime):
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return format % (value.year, value.month, value.day,
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value.hour, value.minute, value.second,
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value.microsecond)
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elif isinstance(value, datetime_date):
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return format % (value.year, value.month, value.day,
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0, 0, 0, 0)
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else:
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raise TypeError("SQLite DateTime type only accepts Python "
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"datetime and date objects as input.")
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return process
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def result_processor(self, dialect, coltype):
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if self._reg:
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return processors.str_to_datetime_processor_factory(
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self._reg, datetime.datetime)
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else:
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return processors.str_to_datetime
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class DATE(_DateTimeMixin, sqltypes.Date):
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_storage_format = "%04d-%02d-%02d"
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def bind_processor(self, dialect):
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datetime_date = datetime.date
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format = self._storage_format
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def process(value):
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if value is None:
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return None
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elif isinstance(value, datetime_date):
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return format % (value.year, value.month, value.day)
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else:
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raise TypeError("SQLite Date type only accepts Python "
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"date objects as input.")
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return process
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def result_processor(self, dialect, coltype):
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if self._reg:
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return processors.str_to_datetime_processor_factory(
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self._reg, datetime.date)
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else:
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return processors.str_to_date
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class TIME(_DateTimeMixin, sqltypes.Time):
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_storage_format = "%02d:%02d:%02d.%06d"
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def bind_processor(self, dialect):
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datetime_time = datetime.time
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format = self._storage_format
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def process(value):
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if value is None:
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return None
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elif isinstance(value, datetime_time):
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return format % (value.hour, value.minute, value.second,
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value.microsecond)
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else:
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raise TypeError("SQLite Time type only accepts Python "
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"time objects as input.")
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return process
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def result_processor(self, dialect, coltype):
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if self._reg:
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return processors.str_to_datetime_processor_factory(
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self._reg, datetime.time)
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else:
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return processors.str_to_time
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colspecs = {
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sqltypes.Date: DATE,
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sqltypes.DateTime: DATETIME,
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sqltypes.Time: TIME,
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}
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ischema_names = {
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'BLOB': sqltypes.BLOB,
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'BOOL': sqltypes.BOOLEAN,
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'BOOLEAN': sqltypes.BOOLEAN,
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'CHAR': sqltypes.CHAR,
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'DATE': sqltypes.DATE,
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'DATETIME': sqltypes.DATETIME,
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'DECIMAL': sqltypes.DECIMAL,
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'FLOAT': sqltypes.FLOAT,
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'INT': sqltypes.INTEGER,
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'INTEGER': sqltypes.INTEGER,
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'NUMERIC': sqltypes.NUMERIC,
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'REAL': sqltypes.Numeric,
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'SMALLINT': sqltypes.SMALLINT,
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'TEXT': sqltypes.TEXT,
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'TIME': sqltypes.TIME,
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'TIMESTAMP': sqltypes.TIMESTAMP,
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'VARCHAR': sqltypes.VARCHAR,
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}
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class SQLiteCompiler(compiler.SQLCompiler):
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extract_map = util.update_copy(
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compiler.SQLCompiler.extract_map,
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{
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'month': '%m',
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'day': '%d',
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'year': '%Y',
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'second': '%S',
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'hour': '%H',
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'doy': '%j',
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'minute': '%M',
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'epoch': '%s',
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'dow': '%w',
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'week': '%W'
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})
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def visit_now_func(self, fn, **kw):
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return "CURRENT_TIMESTAMP"
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def visit_char_length_func(self, fn, **kw):
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return "length%s" % self.function_argspec(fn)
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def visit_cast(self, cast, **kwargs):
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if self.dialect.supports_cast:
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return super(SQLiteCompiler, self).visit_cast(cast)
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else:
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return self.process(cast.clause)
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def visit_extract(self, extract, **kw):
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try:
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return "CAST(STRFTIME('%s', %s) AS INTEGER)" % (
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self.extract_map[extract.field], self.process(extract.expr, **kw))
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except KeyError:
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raise exc.ArgumentError(
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"%s is not a valid extract argument." % extract.field)
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def limit_clause(self, select):
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text = ""
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if select._limit is not None:
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text += " \n LIMIT " + str(select._limit)
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if select._offset is not None:
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if select._limit is None:
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text += " \n LIMIT -1"
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text += " OFFSET " + str(select._offset)
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else:
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text += " OFFSET 0"
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return text
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def for_update_clause(self, select):
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# sqlite has no "FOR UPDATE" AFAICT
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return ''
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class SQLiteDDLCompiler(compiler.DDLCompiler):
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def get_column_specification(self, column, **kwargs):
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colspec = self.preparer.format_column(column) + " " + self.dialect.type_compiler.process(column.type)
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default = self.get_column_default_string(column)
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if default is not None:
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colspec += " DEFAULT " + default
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if not column.nullable:
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colspec += " NOT NULL"
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if column.primary_key and \
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column.table.kwargs.get('sqlite_autoincrement', False) and \
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len(column.table.primary_key.columns) == 1 and \
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isinstance(column.type, sqltypes.Integer) and \
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not column.foreign_keys:
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colspec += " PRIMARY KEY AUTOINCREMENT"
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return colspec
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def visit_primary_key_constraint(self, constraint):
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# for columns with sqlite_autoincrement=True,
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# the PRIMARY KEY constraint can only be inline
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# with the column itself.
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if len(constraint.columns) == 1:
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c = list(constraint)[0]
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if c.primary_key and \
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c.table.kwargs.get('sqlite_autoincrement', False) and \
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isinstance(c.type, sqltypes.Integer) and \
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not c.foreign_keys:
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return ''
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return super(SQLiteDDLCompiler, self).\
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visit_primary_key_constraint(constraint)
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def visit_create_index(self, create):
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index = create.element
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preparer = self.preparer
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text = "CREATE "
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if index.unique:
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text += "UNIQUE "
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text += "INDEX %s ON %s (%s)" \
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% (preparer.format_index(index,
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name=self._validate_identifier(index.name, True)),
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preparer.format_table(index.table, use_schema=False),
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', '.join(preparer.quote(c.name, c.quote)
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for c in index.columns))
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return text
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class SQLiteTypeCompiler(compiler.GenericTypeCompiler):
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def visit_large_binary(self, type_):
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return self.visit_BLOB(type_)
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class SQLiteIdentifierPreparer(compiler.IdentifierPreparer):
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reserved_words = set([
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'add', 'after', 'all', 'alter', 'analyze', 'and', 'as', 'asc',
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'attach', 'autoincrement', 'before', 'begin', 'between', 'by',
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'cascade', 'case', 'cast', 'check', 'collate', 'column', 'commit',
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'conflict', 'constraint', 'create', 'cross', 'current_date',
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'current_time', 'current_timestamp', 'database', 'default',
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'deferrable', 'deferred', 'delete', 'desc', 'detach', 'distinct',
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'drop', 'each', 'else', 'end', 'escape', 'except', 'exclusive',
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'explain', 'false', 'fail', 'for', 'foreign', 'from', 'full', 'glob',
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'group', 'having', 'if', 'ignore', 'immediate', 'in', 'index',
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'indexed', 'initially', 'inner', 'insert', 'instead', 'intersect', 'into', 'is',
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'isnull', 'join', 'key', 'left', 'like', 'limit', 'match', 'natural',
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'not', 'notnull', 'null', 'of', 'offset', 'on', 'or', 'order', 'outer',
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'plan', 'pragma', 'primary', 'query', 'raise', 'references',
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'reindex', 'rename', 'replace', 'restrict', 'right', 'rollback',
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'row', 'select', 'set', 'table', 'temp', 'temporary', 'then', 'to',
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'transaction', 'trigger', 'true', 'union', 'unique', 'update', 'using',
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'vacuum', 'values', 'view', 'virtual', 'when', 'where',
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])
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def format_index(self, index, use_schema=True, name=None):
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"""Prepare a quoted index and schema name."""
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if name is None:
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name = index.name
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result = self.quote(name, index.quote)
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if not self.omit_schema and use_schema and getattr(index.table, "schema", None):
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result = self.quote_schema(index.table.schema, index.table.quote_schema) + "." + result
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return result
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class SQLiteDialect(default.DefaultDialect):
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name = 'sqlite'
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supports_alter = False
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supports_unicode_statements = True
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supports_unicode_binds = True
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supports_default_values = True
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supports_empty_insert = False
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supports_cast = True
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default_paramstyle = 'qmark'
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statement_compiler = SQLiteCompiler
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ddl_compiler = SQLiteDDLCompiler
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type_compiler = SQLiteTypeCompiler
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preparer = SQLiteIdentifierPreparer
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ischema_names = ischema_names
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colspecs = colspecs
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isolation_level = None
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supports_cast = True
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supports_default_values = True
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def __init__(self, isolation_level=None, native_datetime=False, **kwargs):
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default.DefaultDialect.__init__(self, **kwargs)
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if isolation_level and isolation_level not in ('SERIALIZABLE',
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'READ UNCOMMITTED'):
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raise exc.ArgumentError("Invalid value for isolation_level. "
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"Valid isolation levels for sqlite are 'SERIALIZABLE' and "
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"'READ UNCOMMITTED'.")
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self.isolation_level = isolation_level
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# this flag used by pysqlite dialect, and perhaps others in the
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# future, to indicate the driver is handling date/timestamp
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# conversions (and perhaps datetime/time as well on some
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# hypothetical driver ?)
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self.native_datetime = native_datetime
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if self.dbapi is not None:
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self.supports_default_values = \
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self.dbapi.sqlite_version_info >= (3, 3, 8)
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self.supports_cast = \
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self.dbapi.sqlite_version_info >= (3, 2, 3)
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def on_connect(self):
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if self.isolation_level is not None:
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if self.isolation_level == 'READ UNCOMMITTED':
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isolation_level = 1
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else:
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isolation_level = 0
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def connect(conn):
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cursor = conn.cursor()
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cursor.execute("PRAGMA read_uncommitted = %d" % isolation_level)
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cursor.close()
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return connect
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else:
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return None
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@reflection.cache
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def get_table_names(self, connection, schema=None, **kw):
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if schema is not None:
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qschema = self.identifier_preparer.quote_identifier(schema)
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master = '%s.sqlite_master' % qschema
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s = ("SELECT name FROM %s "
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"WHERE type='table' ORDER BY name") % (master,)
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rs = connection.execute(s)
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else:
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try:
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s = ("SELECT name FROM "
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" (SELECT * FROM sqlite_master UNION ALL "
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" SELECT * FROM sqlite_temp_master) "
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"WHERE type='table' ORDER BY name")
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rs = connection.execute(s)
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except exc.DBAPIError:
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raise
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s = ("SELECT name FROM sqlite_master "
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"WHERE type='table' ORDER BY name")
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rs = connection.execute(s)
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return [row[0] for row in rs]
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def has_table(self, connection, table_name, schema=None):
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quote = self.identifier_preparer.quote_identifier
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if schema is not None:
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pragma = "PRAGMA %s." % quote(schema)
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else:
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pragma = "PRAGMA "
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qtable = quote(table_name)
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cursor = _pragma_cursor(connection.execute("%stable_info(%s)" % (pragma, qtable)))
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row = cursor.fetchone()
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# consume remaining rows, to work around
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# http://www.sqlite.org/cvstrac/tktview?tn=1884
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while cursor.fetchone() is not None:
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pass
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return (row is not None)
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@reflection.cache
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def get_view_names(self, connection, schema=None, **kw):
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if schema is not None:
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qschema = self.identifier_preparer.quote_identifier(schema)
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master = '%s.sqlite_master' % qschema
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s = ("SELECT name FROM %s "
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"WHERE type='view' ORDER BY name") % (master,)
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rs = connection.execute(s)
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else:
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try:
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s = ("SELECT name FROM "
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" (SELECT * FROM sqlite_master UNION ALL "
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" SELECT * FROM sqlite_temp_master) "
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"WHERE type='view' ORDER BY name")
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rs = connection.execute(s)
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except exc.DBAPIError:
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raise
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s = ("SELECT name FROM sqlite_master "
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"WHERE type='view' ORDER BY name")
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rs = connection.execute(s)
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return [row[0] for row in rs]
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@reflection.cache
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def get_view_definition(self, connection, view_name, schema=None, **kw):
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quote = self.identifier_preparer.quote_identifier
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if schema is not None:
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qschema = self.identifier_preparer.quote_identifier(schema)
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master = '%s.sqlite_master' % qschema
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s = ("SELECT sql FROM %s WHERE name = '%s'"
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"AND type='view'") % (master, view_name)
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rs = connection.execute(s)
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else:
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try:
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s = ("SELECT sql FROM "
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" (SELECT * FROM sqlite_master UNION ALL "
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" SELECT * FROM sqlite_temp_master) "
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"WHERE name = '%s' "
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"AND type='view'") % view_name
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rs = connection.execute(s)
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except exc.DBAPIError:
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raise
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s = ("SELECT sql FROM sqlite_master WHERE name = '%s' "
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"AND type='view'") % view_name
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rs = connection.execute(s)
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result = rs.fetchall()
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if result:
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return result[0].sql
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@reflection.cache
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def get_columns(self, connection, table_name, schema=None, **kw):
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quote = self.identifier_preparer.quote_identifier
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if schema is not None:
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pragma = "PRAGMA %s." % quote(schema)
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else:
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pragma = "PRAGMA "
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qtable = quote(table_name)
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c = _pragma_cursor(connection.execute("%stable_info(%s)" % (pragma, qtable)))
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found_table = False
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columns = []
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while True:
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row = c.fetchone()
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if row is None:
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break
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(name, type_, nullable, default, has_default, primary_key) = (row[1], row[2].upper(), not row[3], row[4], row[4] is not None, row[5])
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name = re.sub(r'^\"|\"$', '', name)
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if default:
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default = re.sub(r"^\'|\'$", '', default)
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match = re.match(r'(\w+)(\(.*?\))?', type_)
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if match:
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coltype = match.group(1)
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args = match.group(2)
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else:
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coltype = "VARCHAR"
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args = ''
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try:
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coltype = self.ischema_names[coltype]
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except KeyError:
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util.warn("Did not recognize type '%s' of column '%s'" %
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(coltype, name))
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coltype = sqltypes.NullType
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if args is not None:
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args = re.findall(r'(\d+)', args)
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coltype = coltype(*[int(a) for a in args])
|
|
|
|
columns.append({
|
|
'name' : name,
|
|
'type' : coltype,
|
|
'nullable' : nullable,
|
|
'default' : default,
|
|
'primary_key': primary_key
|
|
})
|
|
return columns
|
|
|
|
@reflection.cache
|
|
def get_primary_keys(self, connection, table_name, schema=None, **kw):
|
|
cols = self.get_columns(connection, table_name, schema, **kw)
|
|
pkeys = []
|
|
for col in cols:
|
|
if col['primary_key']:
|
|
pkeys.append(col['name'])
|
|
return pkeys
|
|
|
|
@reflection.cache
|
|
def get_foreign_keys(self, connection, table_name, schema=None, **kw):
|
|
quote = self.identifier_preparer.quote_identifier
|
|
if schema is not None:
|
|
pragma = "PRAGMA %s." % quote(schema)
|
|
else:
|
|
pragma = "PRAGMA "
|
|
qtable = quote(table_name)
|
|
c = _pragma_cursor(connection.execute("%sforeign_key_list(%s)" % (pragma, qtable)))
|
|
fkeys = []
|
|
fks = {}
|
|
while True:
|
|
row = c.fetchone()
|
|
if row is None:
|
|
break
|
|
(constraint_name, rtbl, lcol, rcol) = (row[0], row[2], row[3], row[4])
|
|
rtbl = re.sub(r'^\"|\"$', '', rtbl)
|
|
lcol = re.sub(r'^\"|\"$', '', lcol)
|
|
rcol = re.sub(r'^\"|\"$', '', rcol)
|
|
try:
|
|
fk = fks[constraint_name]
|
|
except KeyError:
|
|
fk = {
|
|
'name' : constraint_name,
|
|
'constrained_columns' : [],
|
|
'referred_schema' : None,
|
|
'referred_table' : rtbl,
|
|
'referred_columns' : []
|
|
}
|
|
fkeys.append(fk)
|
|
fks[constraint_name] = fk
|
|
|
|
# look up the table based on the given table's engine, not 'self',
|
|
# since it could be a ProxyEngine
|
|
if lcol not in fk['constrained_columns']:
|
|
fk['constrained_columns'].append(lcol)
|
|
if rcol not in fk['referred_columns']:
|
|
fk['referred_columns'].append(rcol)
|
|
return fkeys
|
|
|
|
@reflection.cache
|
|
def get_indexes(self, connection, table_name, schema=None, **kw):
|
|
quote = self.identifier_preparer.quote_identifier
|
|
if schema is not None:
|
|
pragma = "PRAGMA %s." % quote(schema)
|
|
else:
|
|
pragma = "PRAGMA "
|
|
include_auto_indexes = kw.pop('include_auto_indexes', False)
|
|
qtable = quote(table_name)
|
|
c = _pragma_cursor(connection.execute("%sindex_list(%s)" % (pragma, qtable)))
|
|
indexes = []
|
|
while True:
|
|
row = c.fetchone()
|
|
if row is None:
|
|
break
|
|
# ignore implicit primary key index.
|
|
# http://www.mail-archive.com/sqlite-users@sqlite.org/msg30517.html
|
|
elif not include_auto_indexes and row[1].startswith('sqlite_autoindex'):
|
|
continue
|
|
|
|
indexes.append(dict(name=row[1], column_names=[], unique=row[2]))
|
|
# loop thru unique indexes to get the column names.
|
|
for idx in indexes:
|
|
c = connection.execute("%sindex_info(%s)" % (pragma, quote(idx['name'])))
|
|
cols = idx['column_names']
|
|
while True:
|
|
row = c.fetchone()
|
|
if row is None:
|
|
break
|
|
cols.append(row[2])
|
|
return indexes
|
|
|
|
|
|
def _pragma_cursor(cursor):
|
|
"""work around SQLite issue whereby cursor.description is blank when PRAGMA returns no rows."""
|
|
|
|
if cursor.closed:
|
|
cursor._fetchone_impl = lambda: None
|
|
return cursor
|