def get_related_objects(instances, filters=None):
queryset = None
apply_filters = mk_filter_function(filters)
# functioning defining a relationship
if type(rel_obj_descriptor) in (types.FunctionType, types.MethodType):
return rel_obj_descriptor(instances, apply_filters)
# FK from instance to a related object
elif type(rel_obj_descriptor) == ReverseSingleRelatedObjectDescriptor:
field = rel_obj_descriptor.field
rel_obj_attr = field.get_foreign_related_value
instance_attr = field.get_local_related_value
query = {'%s__in' % field.related_query_name(): instances}
rel_mgr = field.rel.to._default_manager
# If the related manager indicates that it should be used for related
# fields, respect that.
if getattr(rel_mgr, 'use_for_related_fields', False):
queryset = rel_mgr
else:
queryset = QuerySet(field.rel.to)
queryset = queryset.filter(**query).only('pk')
table = instances[0]._meta.db_table
pk_field = instances[0]._meta.pk.column
related_table = field.related_field.model._meta.db_table
if table == related_table:
# XXX hack: assuming django uses T2 for joining two tables of same name
table = 'T2'
queryset = queryset.extra(
select={INPUT_ATTR_PREFIX: '%s.%s' % (table, pk_field)})
# reverse FK from instance to related objects with FK to the instance
elif type(rel_obj_descriptor) == ForeignRelatedObjectsDescriptor:
rel_field = rel_obj_descriptor.related.field
rel_obj_attr = rel_field.get_local_related_value
rel_column = rel_field.column
rel_model = rel_obj_descriptor.related.model
rel_mgr = rel_model._default_manager.__class__()
rel_mgr.model = rel_model
query = {'%s__in' % rel_field.name: instances}
queryset = rel_mgr.get_queryset().filter(**query).only('pk')
queryset = queryset.extra(
select={INPUT_ATTR_PREFIX: '%s' % rel_column})
# M2M from instance to related objects
elif type(rel_obj_descriptor) in (ReverseManyRelatedObjectsDescriptor,
ManyRelatedObjectsDescriptor):
db = router.db_for_read(instance.__class__, instance=instance)
connection = connections[db]
mgr = rel_obj_descriptor.__get__(instance)
query = {'%s__in' % mgr.query_field_name: instances}
queryset = super(mgr.__class__,
mgr).get_queryset().filter(**query).only('pk')
fk = mgr.through._meta.get_field(mgr.source_field_name)
join_table = mgr.through._meta.db_table
qn = connection.ops.quote_name
queryset = queryset.extra(select=dict(
('%s%s' % (INPUT_ATTR_PREFIX, f.attname),
'%s.%s' % (qn(join_table), qn(f.column)))
for f in fk.local_related_fields))
# if you just do 'if queryset', that triggers query execution because
# python checks length of the enumerable. to prevent query execution, check
# if queryset is not None.
if queryset is not None:
return apply_filters(queryset)
return []
def get_related_objects(instances, filters=None):
queryset = None
apply_filters = mk_filter_function(filters)
# functioning defining a relationship
if type(rel_obj_descriptor) in (types.FunctionType, types.MethodType):
return rel_obj_descriptor(instances, apply_filters)
# FK from instance to a related object
elif type(rel_obj_descriptor) in (ForwardManyToOneDescriptor, ForwardOneToOneDescriptor):
field = rel_obj_descriptor.field
rel_obj_attr = field.get_foreign_related_value
instance_attr = field.get_local_related_value
query = {'%s__in' % field.related_query_name(): instances}
rel_mgr = field.rel.to._default_manager
# If the related manager indicates that it should be used for related
# fields, respect that.
if getattr(rel_mgr, 'use_for_related_fields', False):
queryset = rel_mgr
else:
queryset = QuerySet(field.rel.to)
queryset = queryset.filter(**query).only('pk')
table = instances[0]._meta.db_table
pk_field = instances[0]._meta.pk.column
related_table = field.rel.model._meta.db_table
if table == related_table:
# XXX hack: assuming django uses T2 for joining two tables of same name
table = 'T2'
queryset = queryset.extra(select={INPUT_ATTR_PREFIX: '%s.%s' % (table, pk_field)})
# reverse FK from instance to related objects with FK to the instance
elif type(rel_obj_descriptor) in (ReverseManyToOneDescriptor, ReverseOneToOneDescriptor):
rel_obj = rel_obj_descriptor.related if (type(rel_obj_descriptor) == ReverseOneToOneDescriptor) else \
rel_obj_descriptor.rel
rel_field = rel_obj.field
rel_obj_attr = rel_field.get_local_related_value
rel_column = rel_field.column
rel_model = rel_obj.related_model
rel_mgr = rel_model._default_manager.__class__()
rel_mgr.model = rel_model
query = {'%s__in' % rel_field.name: instances}
queryset = rel_mgr.get_queryset().filter(**query).only('pk')
queryset = queryset.extra(select={INPUT_ATTR_PREFIX: '%s' % rel_column})
# M2M from instance to related objects
elif type(rel_obj_descriptor) in (ReverseManyToOneDescriptor, ManyToManyDescriptor):
db = router.db_for_read(instance.__class__, instance=instance)
connection = connections[db]
mgr = rel_obj_descriptor.__get__(instance)
query = {'%s__in' % mgr.query_field_name: instances}
queryset = super(mgr.__class__, mgr).get_queryset().filter(**query).only('pk')
fk = mgr.through._meta.get_field(mgr.source_field_name)
join_table = mgr.through._meta.db_table
qn = connection.ops.quote_name
queryset = queryset.extra(select=dict(
('%s%s' % (INPUT_ATTR_PREFIX, f.attname),
'%s.%s' % (qn(join_table), qn(f.column))) for f in fk.local_related_fields))
# if you just do 'if queryset', that triggers query execution because
# python checks length of the enumerable. to prevent query execution, check
# if queryset is not None.
if queryset is not None:
return apply_filters(queryset)
return []
