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magic-removal: Refactored ManyRelatedObjectsDescriptor and
ReverseManyRelatedObjectsDescriptor to remove duplication and simplify code, with some small related cleanups. git-svn-id: http://code.djangoproject.com/svn/django/branches/magic-removal@2605 bcc190cf-cafb-0310-a4f2-bffc1f526a37
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Luke Plant
parent
0d6f2f8707
commit
2eb2bad2e1
@ -225,30 +225,72 @@ class ForeignRelatedObjectsDescriptor(object):
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for obj in value:
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manager.add(obj)
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def _add_m2m_items(rel_manager_inst, managerclass, rel_model, join_table, source_col_name,
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target_col_name, source_pk_val, *objs):
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# Utility function used by the ManyRelatedObjectsDescriptors
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# to do addition to a many-to-many field.
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# rel_manager_inst: the RelatedManager instance
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# managerclass: class that can create and save new objects
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# rel_model: the model class of the 'related' object
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def create_many_related_manager(superclass):
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"""Creates a manager that subclasses 'superclass' (which is a Manager)
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and adds behaviour for many-to-many related objects."""
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class ManyRelatedManager(superclass):
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def __init__(self, model=None, core_filters=None, instance=None, symmetrical=None,
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join_table=None, source_col_name=None, target_col_name=None):
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super(ManyRelatedManager, self).__init__()
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self.core_filters = core_filters
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self.model = model
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self.symmetrical = symmetrical
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self.instance = instance
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self.join_table = join_table
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self.source_col_name = source_col_name
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self.target_col_name = target_col_name
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if instance:
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self._pk_val = self.instance._get_pk_val()
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def get_query_set(self):
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return superclass.get_query_set(self).filter(**(self.core_filters))
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def add(self, *objs):
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self._add_items(self.source_col_name, self.target_col_name, *objs)
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# If this is a symmetrical m2m relation to self, add the mirror entry in the m2m table
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if self.symmetrical:
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self._add_items(self.target_col_name, self.source_col_name, *objs)
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add.alters_data = True
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def remove(self, *objs):
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self._remove_items(self.source_col_name, self.target_col_name, *objs)
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# If this is a symmetrical m2m relation to self, remove the mirror entry in the m2m table
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if self.symmetrical:
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self._remove_items(self.target_col_name, self.source_col_name, *objs)
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remove.alters_data = True
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def clear(self):
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self._clear_items(self.source_col_name)
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# If this is a symmetrical m2m relation to self, clear the mirror entry in the m2m table
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if self.symmetrical:
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self._clear_items(self.target_col_name)
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clear.alters_data = True
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def create(self, **kwargs):
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new_obj = self.model(**kwargs)
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new_obj.save()
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self.add(new_obj)
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return new_obj
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create.alters_data = True
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def _add_items(self, source_col_name, target_col_name, *objs):
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# join_table: name of the m2m link table
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# source_col_name: the PK colname in join_table for the source object
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# target_col_name: the PK colname in join_table for the target object
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# source_pk_val: the primary key for the source object
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# *objs - objects to add
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from django.db import connection
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rel_opts = rel_model._meta
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# Add the newly created or already existing objects to the join table.
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# First find out which items are already added, to avoid adding them twice
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new_ids = set([obj._get_pk_val() for obj in objs])
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cursor = connection.cursor()
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cursor.execute("SELECT %s FROM %s WHERE %s = %%s AND %s IN (%s)" % \
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(target_col_name, join_table, source_col_name,
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(target_col_name, self.join_table, source_col_name,
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target_col_name, ",".join(['%s'] * len(new_ids))),
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[source_pk_val] + list(new_ids))
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[self._pk_val] + list(new_ids))
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if cursor.rowcount is not None and cursor.rowcount != 0:
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existing_ids = set([row[0] for row in cursor.fetchmany(cursor.rowcount)])
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else:
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@ -257,47 +299,38 @@ def _add_m2m_items(rel_manager_inst, managerclass, rel_model, join_table, source
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# Add the ones that aren't there already
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for obj_id in (new_ids - existing_ids):
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cursor.execute("INSERT INTO %s (%s, %s) VALUES (%%s, %%s)" % \
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(join_table, source_col_name, target_col_name),
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[source_pk_val, obj_id])
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(self.join_table, source_col_name, target_col_name),
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[self._pk_val, obj_id])
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transaction.commit_unless_managed()
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def _remove_m2m_items(rel_model, join_table, source_col_name,
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target_col_name, source_pk_val, *objs):
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# Utility function used by the ManyRelatedObjectsDescriptors
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# to do removal from a many-to-many field.
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# rel_model: the model class of the 'related' object
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# join_table: name of the m2m link table
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def _remove_items(self, source_col_name, target_col_name, *objs):
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# source_col_name: the PK colname in join_table for the source object
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# target_col_name: the PK colname in join_table for the target object
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# source_pk_val: the primary key for the source object
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# *objs - objects to remove
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from django.db import connection
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rel_opts = rel_model._meta
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for obj in objs:
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if not isinstance(obj, rel_model):
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raise ValueError, "objects to remove() must be %s instances" % rel_opts.object_name
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if not isinstance(obj, self.model):
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raise ValueError, "objects to remove() must be %s instances" % self.model._meta.object_name
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# Remove the specified objects from the join table
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cursor = connection.cursor()
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for obj in objs:
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cursor.execute("DELETE FROM %s WHERE %s = %%s AND %s = %%s" % \
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(join_table, source_col_name, target_col_name),
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[source_pk_val, obj._get_pk_val()])
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(self.join_table, source_col_name, target_col_name),
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[self._pk_val, obj._get_pk_val()])
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transaction.commit_unless_managed()
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def _clear_m2m_items(join_table, source_col_name, source_pk_val):
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# Utility function used by the ManyRelatedObjectsDescriptors
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# to clear all from a many-to-many field.
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# join_table: name of the m2m link table
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def _clear_items(self, source_col_name):
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# source_col_name: the PK colname in join_table for the source object
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# source_pk_val: the primary key for the source object
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from django.db import connection
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cursor = connection.cursor()
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cursor.execute("DELETE FROM %s WHERE %s = %%s" % \
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(join_table, source_col_name),
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[source_pk_val])
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(self.join_table, source_col_name),
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[self._pk_val])
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transaction.commit_unless_managed()
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return ManyRelatedManager
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class ManyRelatedObjectsDescriptor(object):
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# This class provides the functionality that makes the related-object
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# managers available as attributes on a model class, for fields that have
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@ -312,48 +345,22 @@ class ManyRelatedObjectsDescriptor(object):
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if instance is None:
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raise AttributeError, "Manager must be accessed via instance"
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rel_field = self.related.field
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rel_model = self.related.model
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qn = backend.quote_name
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this_opts = instance.__class__._meta
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rel_opts = rel_model._meta
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join_table = qn(self.related.field.m2m_db_table())
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source_col_name = qn(self.related.field.m2m_reverse_name())
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target_col_name = qn(self.related.field.m2m_column_name())
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# Dynamically create a class that subclasses the related
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# model's default manager.
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superclass = self.related.model._default_manager.__class__
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rel_model = self.related.model
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superclass = rel_model._default_manager.__class__
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RelatedManager = create_many_related_manager(superclass)
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class RelatedManager(superclass):
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def get_query_set(self):
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return superclass.get_query_set(self).filter(**(self.core_filters))
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def add(self, *objs):
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_add_m2m_items(self, superclass, rel_model, join_table, source_col_name,
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target_col_name, instance._get_pk_val(), *objs)
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add.alters_data = True
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def remove(self, *objs):
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_remove_m2m_items(rel_model, join_table, source_col_name,
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target_col_name, instance._get_pk_val(), *objs)
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remove.alters_data = True
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def clear(self):
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_clear_m2m_items(join_table, source_col_name, instance._get_pk_val())
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clear.alters_data = True
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def create(self, **kwargs):
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new_obj = self.model(**kwargs)
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new_obj.save()
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self.add(new_obj)
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return new_obj
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create.alters_data = True
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manager = RelatedManager()
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manager.core_filters = {'%s__pk' % rel_field.name: instance._get_pk_val()}
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manager.model = self.related.model
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qn = backend.quote_name
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manager = RelatedManager(
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model=rel_model,
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core_filters={'%s__pk' % self.related.field.name: instance._get_pk_val()},
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instance=instance,
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symmetrical=False,
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join_table=qn(self.related.field.m2m_db_table()),
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source_col_name=qn(self.related.field.m2m_reverse_name()),
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target_col_name=qn(self.related.field.m2m_column_name())
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)
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return manager
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@ -380,61 +387,22 @@ class ReverseManyRelatedObjectsDescriptor(object):
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if instance is None:
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raise AttributeError, "Manager must be accessed via instance"
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qn = backend.quote_name
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this_opts = instance.__class__._meta
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symmetrical = self.field.rel.symmetrical
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rel_model = self.field.rel.to
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rel_opts = rel_model._meta
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join_table = qn(self.field.m2m_db_table())
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source_col_name = qn(self.field.m2m_column_name())
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target_col_name = qn(self.field.m2m_reverse_name())
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# Dynamically create a class that subclasses the related
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# model's default manager.
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rel_model=self.field.rel.to
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superclass = rel_model._default_manager.__class__
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RelatedManager = create_many_related_manager(superclass)
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class RelatedManager(superclass):
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def get_query_set(self):
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return superclass.get_query_set(self).filter(**(self.core_filters))
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def add(self, *objs):
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_add_m2m_items(self, superclass, rel_model, join_table, source_col_name,
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target_col_name, instance._get_pk_val(), *objs)
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# If this is a symmetrical m2m relation to self, add the mirror entry in the m2m table
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if instance.__class__ == rel_model and symmetrical:
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_add_m2m_items(self, superclass, rel_model, join_table, target_col_name,
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source_col_name, instance._get_pk_val(), *objs)
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add.alters_data = True
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def remove(self, *objs):
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_remove_m2m_items(rel_model, join_table, source_col_name,
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target_col_name, instance._get_pk_val(), *objs)
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# If this is a symmetrical m2m relation to self, remove the mirror entry in the m2m table
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if instance.__class__ == rel_model and symmetrical:
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_remove_m2m_items(rel_model, join_table, target_col_name,
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source_col_name, instance._get_pk_val(), *objs)
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remove.alters_data = True
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def clear(self):
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_clear_m2m_items(join_table, source_col_name, instance._get_pk_val())
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# If this is a symmetrical m2m relation to self, clear the mirror entry in the m2m table
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if instance.__class__ == rel_model and symmetrical:
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_clear_m2m_items(join_table, target_col_name, instance._get_pk_val())
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clear.alters_data = True
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def create(self, **kwargs):
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new_obj = self.model(**kwargs)
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new_obj.save()
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self.add(new_obj)
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return new_obj
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create.alters_data = True
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manager = RelatedManager()
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manager.core_filters = {'%s__pk' % self.field.related_query_name() : instance._get_pk_val()}
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manager.model = rel_model
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qn = backend.quote_name
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manager = RelatedManager(
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model=rel_model,
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core_filters={'%s__pk' % self.field.related_query_name() : instance._get_pk_val()},
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instance=instance,
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symmetrical=(self.field.rel.symmetrical and instance.__class__ == rel_model),
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join_table=qn(self.field.m2m_db_table()),
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source_col_name=qn(self.field.m2m_column_name()),
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target_col_name=qn(self.field.m2m_reverse_name())
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)
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return manager
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