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magic-removal: Added descriptor lookup support for reverse many-to-many relationships -- e.g. site_obj.article_set. For the time being, site_obj.get_article_list(), site_obj.get_article_count(), etc., still work. 

git-svn-id: http://code.djangoproject.com/svn/django/branches/magic-removal@2144 bcc190cf-cafb-0310-a4f2-bffc1f526a37
This commit is contained in:
Adrian Holovaty 2006-01-28 02:08:32 +00:00
parent 322336c382
commit 90a49140a5
1 changed files with 30 additions and 21 deletions
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51
django/db/models/fields/related.py
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@ -67,33 +67,36 @@ class RelatedObjectDescriptor(object):
# managers available as attributes on a model class. # managers available as attributes on a model class.
# In the example "poll.choice_set", the choice_set attribute is a # In the example "poll.choice_set", the choice_set attribute is a
# RelatedObjectDescriptor instance. # RelatedObjectDescriptor instance.
def __init__(self, related): def __init__(self, related, rel_type):
self.related = related # RelatedObject instance self.related = related # RelatedObject instance
self.manager = None self.rel_type = rel_type # Either 'o2m' or 'm2m'
def __get__(self, instance, instance_type=None): def __get__(self, instance, instance_type=None):
if instance is None: if instance is None:
raise AttributeError, "Manager must be accessed via instance" raise AttributeError, "Manager must be accessed via instance"
else: else:
if not self.manager: # Dynamically create a class that subclasses the related
# Dynamically create a class that subclasses the related # model's default manager.
# model's default manager. manager = types.ClassType('RelatedManager', (self.related.model._default_manager.__class__,), {})()
self.manager = types.ClassType('RelatedManager', (self.related.model._default_manager.__class__,), {})()
# Set core_filters on the new manager to limit it to the # Set core_filters on the new manager to limit it to the
# foreign-key relationship. # foreign-key relationship.
rel_field = self.related.field rel_field = self.related.field
self.manager.core_filters = {'%s__%s__exact' % (rel_field.name, rel_field.rel.to._meta.pk.name): getattr(instance, rel_field.rel.get_related_field().attname)}
# Prepare the manager. if self.rel_type == 'o2m':
# TODO: Fix this hack? manager.core_filters = {'%s__%s__exact' % (rel_field.name, rel_field.rel.to._meta.pk.name): getattr(instance, rel_field.rel.get_related_field().attname)}
# We're setting self.manager.klass here because else:
# self.manager._prepare() expects that self.manager.klass is manager.core_filters = {'%s__%s__exact' % (rel_field.name, instance_type._meta.pk.name): instance._get_pk_val()}
# set. This is slightly hackish.
self.manager.klass = self.related.model
self.manager._prepare()
return self.manager # Prepare the manager.
# TODO: Fix this hack?
# We're setting self.manager.klass here because
# self.manager._prepare() expects that self.manager.klass is
# set. This is slightly hackish.
manager.klass = self.related.model
manager._prepare()
return manager
class ForeignKey(RelatedField, Field): class ForeignKey(RelatedField, Field):
empty_strings_allowed = False empty_strings_allowed = False
@ -185,12 +188,12 @@ class ForeignKey(RelatedField, Field):
setattr(cls, 'get_%s' % self.name, curry(cls._get_foreign_key_object, field_with_rel=self)) setattr(cls, 'get_%s' % self.name, curry(cls._get_foreign_key_object, field_with_rel=self))
def contribute_to_related_class(self, cls, related): def contribute_to_related_class(self, cls, related):
setattr(cls, related.get_accessor_name(), RelatedObjectDescriptor(related)) setattr(cls, related.get_accessor_name(), RelatedObjectDescriptor(related, 'o2m'))
# TODO: Delete the rest of this function and RelatedObject.OLD_get_accessor_name() # TODO: Delete the rest of this function and RelatedObject.OLD_get_accessor_name()
# to remove support for old-style related lookup. # to remove support for old-style related lookup.
rel_obj_name = related.OLD_get_accessor_name rel_obj_name = related.OLD_get_accessor_name()
# Add "get_thingie" methods for many-to-one related objects. # Add "get_thingie" methods for many-to-one related objects.
# EXAMPLE: Poll.get_choice() # EXAMPLE: Poll.get_choice()
@ -336,7 +339,13 @@ class ManyToManyField(RelatedField, Field):
setattr(cls, 'set_%s' % self.name, curry(cls._set_many_to_many_objects, field_with_rel=self)) setattr(cls, 'set_%s' % self.name, curry(cls._set_many_to_many_objects, field_with_rel=self))
def contribute_to_related_class(self, cls, related): def contribute_to_related_class(self, cls, related):
setattr(cls, related.get_accessor_name(), RelatedObjectDescriptor(related, 'm2m'))
# TODO: Delete the rest of this function and RelatedObject.OLD_get_accessor_name()
# to remove support for old-style related lookup.
rel_obj_name = related.OLD_get_accessor_name() rel_obj_name = related.OLD_get_accessor_name()
setattr(cls, 'get_%s' % rel_obj_name, curry(cls._get_related_many_to_many, method_name='get_object', rel_class=related.model, rel_field=related.field)) setattr(cls, 'get_%s' % rel_obj_name, curry(cls._get_related_many_to_many, method_name='get_object', rel_class=related.model, rel_field=related.field))
setattr(cls, 'get_%s_count' % rel_obj_name, curry(cls._get_related_many_to_many, method_name='get_count', rel_class=related.model, rel_field=related.field)) setattr(cls, 'get_%s_count' % rel_obj_name, curry(cls._get_related_many_to_many, method_name='get_count', rel_class=related.model, rel_field=related.field))
setattr(cls, 'get_%s_list' % rel_obj_name, curry(cls._get_related_many_to_many, method_name='get_list', rel_class=related.model, rel_field=related.field)) setattr(cls, 'get_%s_list' % rel_obj_name, curry(cls._get_related_many_to_many, method_name='get_list', rel_class=related.model, rel_field=related.field))