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from django.db.models import Manager |
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from django.db.models.query import QuerySet, EmptyQuerySet |
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from django import VERSION as DJANGO_VERSION |
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try: |
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from django.contrib.contenttypes.fields import GenericForeignKey |
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except ImportError: |
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from django.contrib.contenttypes.generic import GenericForeignKey |
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from actstream import settings |
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class GFKManager(Manager): |
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""" |
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A manager that returns a GFKQuerySet instead of a regular QuerySet. |
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""" |
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def get_query_set(self): |
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return GFKQuerySet(self.model) |
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get_queryset = get_query_set |
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def none(self): |
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return self.get_queryset().none() |
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class GFKQuerySet(QuerySet): |
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""" |
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A QuerySet with a fetch_generic_relations() method to bulk fetch |
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all generic related items. Similar to select_related(), but for |
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generic foreign keys. This wraps QuerySet.prefetch_related. |
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""" |
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def fetch_generic_relations(self, *args): |
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qs = self._clone() |
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if not settings.FETCH_RELATIONS: |
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return qs |
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# Backward compatibility patch for |
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# Django versions lower than 1.11.x |
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if DJANGO_VERSION >= (1, 11): |
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private_fields = self.model._meta.private_fields |
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else: |
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private_fields = self.model._meta.virtual_fields |
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gfk_fields = [g for g in private_fields if isinstance(g, GenericForeignKey)] |
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if args: |
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gfk_fields = [g for g in gfk_fields if g.name in args] |
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return qs.prefetch_related(*[g.name for g in gfk_fields]) |
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def _clone(self, klass=None, **kwargs): |
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if DJANGO_VERSION >= (2, 0): |
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return super(GFKQuerySet, self)._clone() |
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for name in ['subclasses', '_annotated']: |
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if hasattr(self, name): |
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kwargs[name] = getattr(self, name) |
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if DJANGO_VERSION < (1, 9): |
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kwargs['klass'] = klass |
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return super(GFKQuerySet, self)._clone(**kwargs) |
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def none(self): |
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clone = self._clone({'klass': EmptyGFKQuerySet}) |
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if hasattr(clone.query, 'set_empty'): |
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clone.query.set_empty() |
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return clone |
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class EmptyGFKQuerySet(GFKQuerySet, EmptyQuerySet): |
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def fetch_generic_relations(self, *args): |
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return self |
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justquick /
django-activity-stream
