diff options
Diffstat (limited to 'google_appengine/lib/django/django/db/models/fields/generic.py')
| -rwxr-xr-x | google_appengine/lib/django/django/db/models/fields/generic.py | 260 |
1 files changed, 260 insertions, 0 deletions
diff --git a/google_appengine/lib/django/django/db/models/fields/generic.py b/google_appengine/lib/django/django/db/models/fields/generic.py new file mode 100755 index 0000000..480ee68 --- /dev/null +++ b/google_appengine/lib/django/django/db/models/fields/generic.py @@ -0,0 +1,260 @@ +""" +Classes allowing "generic" relations through ContentType and object-id fields. +""" + +from django import oldforms +from django.core.exceptions import ObjectDoesNotExist +from django.db import backend +from django.db.models import signals +from django.db.models.fields.related import RelatedField, Field, ManyToManyRel +from django.db.models.loading import get_model +from django.dispatch import dispatcher +from django.utils.functional import curry + +class GenericForeignKey(object): + """ + Provides a generic relation to any object through content-type/object-id + fields. + """ + + def __init__(self, ct_field="content_type", fk_field="object_id"): + self.ct_field = ct_field + self.fk_field = fk_field + + def contribute_to_class(self, cls, name): + # Make sure the fields exist (these raise FieldDoesNotExist, + # which is a fine error to raise here) + self.name = name + self.model = cls + self.cache_attr = "_%s_cache" % name + + # For some reason I don't totally understand, using weakrefs here doesn't work. + dispatcher.connect(self.instance_pre_init, signal=signals.pre_init, sender=cls, weak=False) + + # Connect myself as the descriptor for this field + setattr(cls, name, self) + + def instance_pre_init(self, signal, sender, args, kwargs): + # Handle initalizing an object with the generic FK instaed of + # content-type/object-id fields. + if kwargs.has_key(self.name): + value = kwargs.pop(self.name) + kwargs[self.ct_field] = self.get_content_type(value) + kwargs[self.fk_field] = value._get_pk_val() + + def get_content_type(self, obj): + # Convenience function using get_model avoids a circular import when using this model + ContentType = get_model("contenttypes", "contenttype") + return ContentType.objects.get_for_model(obj) + + def __get__(self, instance, instance_type=None): + if instance is None: + raise AttributeError, "%s must be accessed via instance" % self.name + + try: + return getattr(instance, self.cache_attr) + except AttributeError: + rel_obj = None + ct = getattr(instance, self.ct_field) + if ct: + try: + rel_obj = ct.get_object_for_this_type(pk=getattr(instance, self.fk_field)) + except ObjectDoesNotExist: + pass + setattr(instance, self.cache_attr, rel_obj) + return rel_obj + + def __set__(self, instance, value): + if instance is None: + raise AttributeError, "%s must be accessed via instance" % self.related.opts.object_name + + ct = None + fk = None + if value is not None: + ct = self.get_content_type(value) + fk = value._get_pk_val() + + setattr(instance, self.ct_field, ct) + setattr(instance, self.fk_field, fk) + setattr(instance, self.cache_attr, value) + +class GenericRelation(RelatedField, Field): + """Provides an accessor to generic related objects (i.e. comments)""" + + def __init__(self, to, **kwargs): + kwargs['verbose_name'] = kwargs.get('verbose_name', None) + kwargs['rel'] = GenericRel(to, + related_name=kwargs.pop('related_name', None), + limit_choices_to=kwargs.pop('limit_choices_to', None), + symmetrical=kwargs.pop('symmetrical', True)) + + # Override content-type/object-id field names on the related class + self.object_id_field_name = kwargs.pop("object_id_field", "object_id") + self.content_type_field_name = kwargs.pop("content_type_field", "content_type") + + kwargs['blank'] = True + kwargs['editable'] = False + kwargs['serialize'] = False + Field.__init__(self, **kwargs) + + def get_manipulator_field_objs(self): + choices = self.get_choices_default() + return [curry(oldforms.SelectMultipleField, size=min(max(len(choices), 5), 15), choices=choices)] + + def get_choices_default(self): + return Field.get_choices(self, include_blank=False) + + def flatten_data(self, follow, obj = None): + new_data = {} + if obj: + instance_ids = [instance._get_pk_val() for instance in getattr(obj, self.name).all()] + new_data[self.name] = instance_ids + return new_data + + def m2m_db_table(self): + return self.rel.to._meta.db_table + + def m2m_column_name(self): + return self.object_id_field_name + + def m2m_reverse_name(self): + return self.object_id_field_name + + def contribute_to_class(self, cls, name): + super(GenericRelation, self).contribute_to_class(cls, name) + + # Save a reference to which model this class is on for future use + self.model = cls + + # Add the descriptor for the m2m relation + setattr(cls, self.name, ReverseGenericRelatedObjectsDescriptor(self)) + + def contribute_to_related_class(self, cls, related): + pass + + def set_attributes_from_rel(self): + pass + + def get_internal_type(self): + return "ManyToManyField" + +class ReverseGenericRelatedObjectsDescriptor(object): + """ + This class provides the functionality that makes the related-object + managers available as attributes on a model class, for fields that have + multiple "remote" values and have a GenericRelation defined in their model + (rather than having another model pointed *at* them). In the example + "article.publications", the publications attribute is a + ReverseGenericRelatedObjectsDescriptor instance. + """ + def __init__(self, field): + self.field = field + + def __get__(self, instance, instance_type=None): + if instance is None: + raise AttributeError, "Manager must be accessed via instance" + + # This import is done here to avoid circular import importing this module + from django.contrib.contenttypes.models import ContentType + + # Dynamically create a class that subclasses the related model's + # default manager. + rel_model = self.field.rel.to + superclass = rel_model._default_manager.__class__ + RelatedManager = create_generic_related_manager(superclass) + + manager = RelatedManager( + model = rel_model, + instance = instance, + symmetrical = (self.field.rel.symmetrical and instance.__class__ == rel_model), + join_table = backend.quote_name(self.field.m2m_db_table()), + source_col_name = backend.quote_name(self.field.m2m_column_name()), + target_col_name = backend.quote_name(self.field.m2m_reverse_name()), + content_type = ContentType.objects.get_for_model(self.field.model), + content_type_field_name = self.field.content_type_field_name, + object_id_field_name = self.field.object_id_field_name + ) + + return manager + + def __set__(self, instance, value): + if instance is None: + raise AttributeError, "Manager must be accessed via instance" + + manager = self.__get__(instance) + manager.clear() + for obj in value: + manager.add(obj) + +def create_generic_related_manager(superclass): + """ + Factory function for a manager that subclasses 'superclass' (which is a + Manager) and adds behavior for generic related objects. + """ + + class GenericRelatedObjectManager(superclass): + def __init__(self, model=None, core_filters=None, instance=None, symmetrical=None, + join_table=None, source_col_name=None, target_col_name=None, content_type=None, + content_type_field_name=None, object_id_field_name=None): + + super(GenericRelatedObjectManager, self).__init__() + self.core_filters = core_filters or {} + self.model = model + self.content_type = content_type + self.symmetrical = symmetrical + self.instance = instance + self.join_table = join_table + self.join_table = model._meta.db_table + self.source_col_name = source_col_name + self.target_col_name = target_col_name + self.content_type_field_name = content_type_field_name + self.object_id_field_name = object_id_field_name + self.pk_val = self.instance._get_pk_val() + + def get_query_set(self): + query = { + '%s__pk' % self.content_type_field_name : self.content_type.id, + '%s__exact' % self.object_id_field_name : self.pk_val, + } + return superclass.get_query_set(self).filter(**query) + + def add(self, *objs): + for obj in objs: + setattr(obj, self.content_type_field_name, self.content_type) + setattr(obj, self.object_id_field_name, self.pk_val) + obj.save() + add.alters_data = True + + def remove(self, *objs): + for obj in objs: + obj.delete() + remove.alters_data = True + + def clear(self): + for obj in self.all(): + obj.delete() + clear.alters_data = True + + def create(self, **kwargs): + kwargs[self.content_type_field_name] = self.content_type + kwargs[self.object_id_field_name] = self.pk_val + obj = self.model(**kwargs) + obj.save() + return obj + create.alters_data = True + + return GenericRelatedObjectManager + +class GenericRel(ManyToManyRel): + def __init__(self, to, related_name=None, limit_choices_to=None, symmetrical=True): + self.to = to + self.num_in_admin = 0 + self.related_name = related_name + self.filter_interface = None + self.limit_choices_to = limit_choices_to or {} + self.edit_inline = False + self.raw_id_admin = False + self.symmetrical = symmetrical + self.multiple = True + assert not (self.raw_id_admin and self.filter_interface), \ + "Generic relations may not use both raw_id_admin and filter_interface" |