diff options
| -rw-r--r-- | django/db/models/query.py | 25 |
1 files changed, 14 insertions, 11 deletions
diff --git a/django/db/models/query.py b/django/db/models/query.py index 1bf890e9eb..006feb6427 100644 --- a/django/db/models/query.py +++ b/django/db/models/query.py @@ -1571,20 +1571,23 @@ def prefetch_one_level(instances, prefetcher, lookup, level): rel_attr_val = rel_obj_attr(rel_obj) rel_obj_cache.setdefault(rel_attr_val, []).append(rel_obj) + to_attr, as_attr = lookup.get_current_to_attr(level) + # Make sure `to_attr` does not conflict with a field. + if as_attr and instances: + # We assume that objects retrieved are homogeneous (which is the premise + # of prefetch_related), so what applies to first object applies to all. + model = instances[0].__class__ + try: + model._meta.get_field(to_attr) + except exceptions.FieldDoesNotExist: + pass + else: + msg = 'to_attr={} conflicts with a field on the {} model.' + raise ValueError(msg.format(to_attr, model.__name__)) + for obj in instances: instance_attr_val = instance_attr(obj) vals = rel_obj_cache.get(instance_attr_val, []) - to_attr, as_attr = lookup.get_current_to_attr(level) - - # Check we are not shadowing a field on obj. - if as_attr: - try: - field = obj._meta.get_field(to_attr) - except exceptions.FieldDoesNotExist: - pass - else: - msg = 'to_attr={} conflicts with a field on the {} model.' - raise ValueError(msg.format(to_attr, field.model.__name__)) if single: val = vals[0] if vals else None |