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[1.5.x] Fixed #14694 -- Made `defer()` work with reverse relations

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Reverse o2o fields are now usable with defer.

Backpatch of [6ebf115206]
This commit is contained in:
Tai Lee
2012-11-28 18:16:00 +02:00
committed by Anssi Kääriäinen
parent 54ce0ff7ba
commit a21e8dee76
3 changed files with 50 additions and 5 deletions
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20
django/db/models/sql/query.py
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@@ -585,17 +585,22 @@ class Query(object):
for name in parts[:-1]:
old_model = cur_model
source = opts.get_field_by_name(name)[0]
cur_model = source.rel.to
if is_reverse_o2o(source):
cur_model = source.model
else:
cur_model = source.rel.to
opts = cur_model._meta
# Even if we're "just passing through" this model, we must add
# both the current model's pk and the related reference field
# to the things we select.
must_include[old_model].add(source)
# (if it's not a reverse relation) to the things we select.
if not is_reverse_o2o(source):
must_include[old_model].add(source)
add_to_dict(must_include, cur_model, opts.pk)
field, model, _, _ = opts.get_field_by_name(parts[-1])
if model is None:
model = cur_model
add_to_dict(seen, model, field)
if not is_reverse_o2o(field):
add_to_dict(seen, model, field)
if defer:
# We need to load all fields for each model, except those that
@@ -2032,3 +2037,10 @@ def add_to_dict(data, key, value):
data[key].add(value)
else:
data[key] = set([value])
def is_reverse_o2o(field):
"""
A little helper to check if the given field is reverse-o2o. The field is
expected to be some sort of relation field or related object.
"""
return not hasattr(field, 'rel') and field.field.unique