Projects/dibbler
10
2
Fork 0
Code Issues 21 Pull Requests 1 Actions Activity

Updated SqlAlchemy

Browse Source
This commit is contained in:
Christoffer Viken
2017-04-15 16:27:12 +00:00
parent 2c790e1fe1
commit e3267d4bda
59 changed files with 30236 additions and 26049 deletions
Download Patch File Download Diff File Expand all files Collapse all files

245
sqlalchemy/ext/orderinglist.py
View File

@@ -1,58 +1,78 @@
"""A custom list that manages index/position information for its children.
# ext/orderinglist.py
# Copyright (C) 2005-2017 the SQLAlchemy authors and contributors
# <see AUTHORS file>
#
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
"""A custom list that manages index/position information for contained
elements.
:author: Jason Kirtland
``orderinglist`` is a helper for mutable ordered relationships. It will intercept
list operations performed on a relationship collection and automatically
synchronize changes in list position with an attribute on the related objects.
(See :ref:`advdatamapping_entitycollections` for more information on the general pattern.)
``orderinglist`` is a helper for mutable ordered relationships. It will
intercept list operations performed on a :func:`.relationship`-managed
collection and
automatically synchronize changes in list position onto a target scalar
attribute.
Example: Two tables that store slides in a presentation. Each slide
has a number of bullet points, displayed in order by the 'position'
column on the bullets table. These bullets can be inserted and re-ordered
by your end users, and you need to update the 'position' column of all
affected rows when changes are made.
Example: A ``slide`` table, where each row refers to zero or more entries
in a related ``bullet`` table. The bullets within a slide are
displayed in order based on the value of the ``position`` column in the
``bullet`` table. As entries are reordered in memory, the value of the
``position`` attribute should be updated to reflect the new sort order::
.. sourcecode:: python+sql
slides_table = Table('Slides', metadata,
Column('id', Integer, primary_key=True),
Column('name', String))
Base = declarative_base()
bullets_table = Table('Bullets', metadata,
Column('id', Integer, primary_key=True),
Column('slide_id', Integer, ForeignKey('Slides.id')),
Column('position', Integer),
Column('text', String))
class Slide(Base):
__tablename__ = 'slide'
class Slide(object):
pass
class Bullet(object):
pass
id = Column(Integer, primary_key=True)
name = Column(String)
mapper(Slide, slides_table, properties={
'bullets': relationship(Bullet, order_by=[bullets_table.c.position])
})
mapper(Bullet, bullets_table)
bullets = relationship("Bullet", order_by="Bullet.position")
The standard relationship mapping will produce a list-like attribute on each Slide
containing all related Bullets, but coping with changes in ordering is totally
your responsibility. If you insert a Bullet into that list, there is no
magic- it won't have a position attribute unless you assign it it one, and
you'll need to manually renumber all the subsequent Bullets in the list to
accommodate the insert.
class Bullet(Base):
__tablename__ = 'bullet'
id = Column(Integer, primary_key=True)
slide_id = Column(Integer, ForeignKey('slide.id'))
position = Column(Integer)
text = Column(String)
An ``orderinglist`` can automate this and manage the 'position' attribute on all
related bullets for you.
The standard relationship mapping will produce a list-like attribute on each
``Slide`` containing all related ``Bullet`` objects,
but coping with changes in ordering is not handled automatically.
When appending a ``Bullet`` into ``Slide.bullets``, the ``Bullet.position``
attribute will remain unset until manually assigned. When the ``Bullet``
is inserted into the middle of the list, the following ``Bullet`` objects
will also need to be renumbered.
.. sourcecode:: python+sql
mapper(Slide, slides_table, properties={
'bullets': relationship(Bullet,
collection_class=ordering_list('position'),
order_by=[bullets_table.c.position])
})
mapper(Bullet, bullets_table)
The :class:`.OrderingList` object automates this task, managing the
``position`` attribute on all ``Bullet`` objects in the collection. It is
constructed using the :func:`.ordering_list` factory::
from sqlalchemy.ext.orderinglist import ordering_list
Base = declarative_base()
class Slide(Base):
__tablename__ = 'slide'
id = Column(Integer, primary_key=True)
name = Column(String)
bullets = relationship("Bullet", order_by="Bullet.position",
collection_class=ordering_list('position'))
class Bullet(Base):
__tablename__ = 'bullet'
id = Column(Integer, primary_key=True)
slide_id = Column(Integer, ForeignKey('slide.id'))
position = Column(Integer)
text = Column(String)
With the above mapping the ``Bullet.position`` attribute is managed::
s = Slide()
s.bullets.append(Bullet())
@@ -63,71 +83,98 @@ related bullets for you.
s.bullets[2].position
>>> 2
Use the ``ordering_list`` function to set up the ``collection_class`` on relationships
(as in the mapper example above). This implementation depends on the list
starting in the proper order, so be SURE to put an order_by on your relationship.
The :class:`.OrderingList` construct only works with **changes** to a
collection, and not the initial load from the database, and requires that the
list be sorted when loaded. Therefore, be sure to specify ``order_by`` on the
:func:`.relationship` against the target ordering attribute, so that the
ordering is correct when first loaded.
.. warning:: ``ordering_list`` only provides limited functionality when a primary
key column or unique column is the target of the sort. Since changing the order of
entries often means that two rows must trade values, this is not possible when
the value is constrained by a primary key or unique constraint, since one of the rows
would temporarily have to point to a third available value so that the other row
could take its old value. ``ordering_list`` doesn't do any of this for you,
nor does SQLAlchemy itself.
.. warning::
``ordering_list`` takes the name of the related object's ordering attribute as
an argument. By default, the zero-based integer index of the object's
position in the ``ordering_list`` is synchronized with the ordering attribute:
index 0 will get position 0, index 1 position 1, etc. To start numbering at 1
or some other integer, provide ``count_from=1``.
:class:`.OrderingList` only provides limited functionality when a primary
key column or unique column is the target of the sort. Operations
that are unsupported or are problematic include:
Ordering values are not limited to incrementing integers. Almost any scheme
can implemented by supplying a custom ``ordering_func`` that maps a Python list
index to any value you require.
* two entries must trade values. This is not supported directly in the
case of a primary key or unique constraint because it means at least
one row would need to be temporarily removed first, or changed to
a third, neutral value while the switch occurs.
* an entry must be deleted in order to make room for a new entry.
SQLAlchemy's unit of work performs all INSERTs before DELETEs within a
single flush. In the case of a primary key, it will trade
an INSERT/DELETE of the same primary key for an UPDATE statement in order
to lessen the impact of this limitation, however this does not take place
for a UNIQUE column.
A future feature will allow the "DELETE before INSERT" behavior to be
possible, allevating this limitation, though this feature will require
explicit configuration at the mapper level for sets of columns that
are to be handled in this way.
:func:`.ordering_list` takes the name of the related object's ordering
attribute as an argument. By default, the zero-based integer index of the
object's position in the :func:`.ordering_list` is synchronized with the
ordering attribute: index 0 will get position 0, index 1 position 1, etc. To
start numbering at 1 or some other integer, provide ``count_from=1``.
"""
from sqlalchemy.orm.collections import collection
from sqlalchemy import util
from ..orm.collections import collection, collection_adapter
from .. import util
__all__ = [ 'ordering_list' ]
__all__ = ['ordering_list']
def ordering_list(attr, count_from=None, **kw):
"""Prepares an OrderingList factory for use in mapper definitions.
"""Prepares an :class:`OrderingList` factory for use in mapper definitions.
Returns an object suitable for use as an argument to a Mapper relationship's
``collection_class`` option. Arguments are:
Returns an object suitable for use as an argument to a Mapper
relationship's ``collection_class`` option. e.g.::
attr
from sqlalchemy.ext.orderinglist import ordering_list
class Slide(Base):
__tablename__ = 'slide'
id = Column(Integer, primary_key=True)
name = Column(String)
bullets = relationship("Bullet", order_by="Bullet.position",
collection_class=ordering_list('position'))
:param attr:
Name of the mapped attribute to use for storage and retrieval of
ordering information
count_from (optional)
:param count_from:
Set up an integer-based ordering, starting at ``count_from``. For
example, ``ordering_list('pos', count_from=1)`` would create a 1-based
list in SQL, storing the value in the 'pos' column. Ignored if
``ordering_func`` is supplied.
Passes along any keyword arguments to ``OrderingList`` constructor.
Additional arguments are passed to the :class:`.OrderingList` constructor.
"""
kw = _unsugar_count_from(count_from=count_from, **kw)
return lambda: OrderingList(attr, **kw)
# Ordering utility functions
def count_from_0(index, collection):
"""Numbering function: consecutive integers starting at 0."""
return index
def count_from_1(index, collection):
"""Numbering function: consecutive integers starting at 1."""
return index + 1
def count_from_n_factory(start):
"""Numbering function: consecutive integers starting at arbitrary start."""
@@ -139,8 +186,9 @@ def count_from_n_factory(start):
pass
return f
def _unsugar_count_from(**kw):
"""Builds counting functions from keywrod arguments.
"""Builds counting functions from keyword arguments.
Keyword argument filter, prepares a simple ``ordering_func`` from a
``count_from`` argument, otherwise passes ``ordering_func`` on unchanged.
@@ -156,12 +204,13 @@ def _unsugar_count_from(**kw):
kw['ordering_func'] = count_from_n_factory(count_from)
return kw
class OrderingList(list):
"""A custom list that manages position information for its children.
See the module and __init__ documentation for more details. The
``ordering_list`` factory function is used to configure ``OrderingList``
collections in ``mapper`` relationship definitions.
The :class:`.OrderingList` object is normally set up using the
:func:`.ordering_list` factory function, used in conjunction with
the :func:`.relationship` function.
"""
@@ -176,14 +225,14 @@ class OrderingList(list):
This implementation relies on the list starting in the proper order,
so be **sure** to put an ``order_by`` on your relationship.
ordering_attr
:param ordering_attr:
Name of the attribute that stores the object's order in the
relationship.
ordering_func
Optional. A function that maps the position in the Python list to a
value to store in the ``ordering_attr``. Values returned are
usually (but need not be!) integers.
:param ordering_func: Optional. A function that maps the position in
the Python list to a value to store in the
``ordering_attr``. Values returned are usually (but need not be!)
integers.
An ``ordering_func`` is called with two positional parameters: the
index of the element in the list, and the list itself.
@@ -194,7 +243,7 @@ class OrderingList(list):
like stepped numbering, alphabetical and Fibonacci numbering, see
the unit tests.
reorder_on_append
:param reorder_on_append:
Default False. When appending an object with an existing (non-None)
ordering value, that value will be left untouched unless
``reorder_on_append`` is true. This is an optimization to avoid a
@@ -208,7 +257,7 @@ class OrderingList(list):
making changes, any of whom happen to load this collection even in
passing, all of the sessions would try to "clean up" the numbering
in their commits, possibly causing all but one to fail with a
concurrent modification error. Spooky action at a distance.
concurrent modification error.
Recommend leaving this with the default of False, and just call
``reorder()`` if you're doing ``append()`` operations with
@@ -270,7 +319,10 @@ class OrderingList(list):
def remove(self, entity):
super(OrderingList, self).remove(entity)
self._reorder()
adapter = collection_adapter(self)
if adapter and adapter._referenced_by_owner:
self._reorder()
def pop(self, index=-1):
entity = super(OrderingList, self).pop(index)
@@ -286,8 +338,8 @@ class OrderingList(list):
stop = index.stop or len(self)
if stop < 0:
stop += len(self)
for i in xrange(start, stop, step):
for i in range(start, stop, step):
self.__setitem__(i, entity[i])
else:
self._order_entity(index, entity, True)
@@ -297,7 +349,6 @@ class OrderingList(list):
super(OrderingList, self).__delitem__(index)
self._reorder()
# Py2K
def __setslice__(self, start, end, values):
super(OrderingList, self).__setslice__(start, end, values)
self._reorder()
@@ -305,11 +356,25 @@ class OrderingList(list):
def __delslice__(self, start, end):
super(OrderingList, self).__delslice__(start, end)
self._reorder()
# end Py2K
for func_name, func in locals().items():
if (util.callable(func) and func.func_name == func_name and
not func.__doc__ and hasattr(list, func_name)):
def __reduce__(self):
return _reconstitute, (self.__class__, self.__dict__, list(self))
for func_name, func in list(locals().items()):
if (util.callable(func) and func.__name__ == func_name and
not func.__doc__ and hasattr(list, func_name)):
func.__doc__ = getattr(list, func_name).__doc__
del func_name, func
def _reconstitute(cls, dict_, items):
""" Reconstitute an :class:`.OrderingList`.
This is the adjoint to :meth:`.OrderingList.__reduce__`. It is used for
unpickling :class:`.OrderingList` objects.
"""
obj = cls.__new__(cls)
obj.__dict__.update(dict_)
list.extend(obj, items)
return obj