Commit 0a89a57f authored by Malcolm Tredinnick's avatar Malcolm Tredinnick
Browse files

Fixed deferred fields and select_related() interaction. 

Loading related models when some fields were deferred was resulting in
incorrect offsets being used into the results row, causing the wrong data to be
assigned to attributes.

Refs #10710. This fixes the first of two bugs reported there.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@10383 bcc190cf-cafb-0310-a4f2-bffc1f526a37
parent dded5f52

django/db/models/query.py

+26 −23
Original line number Diff line number Diff line
@@ -908,31 +908,35 @@ def get_cached_row(klass, row, index_start, max_depth=0, cur_depth=0, 
        return None



    restricted = requested is not None

    index_end = index_start + len(klass._meta.fields)

    fields = row[index_start:index_end]

    if not [x for x in fields if x is not None]:

        # If we only have a list of Nones, there was not related object.

        obj = None

    else:

    load_fields = only_load and only_load.get(klass) or None

    if load_fields:

        # Handle deferred fields.

        skip = set()

        init_list = []

            pk_val = fields[klass._meta.pk_index()]

        pk_val = row[index_start + klass._meta.pk_index()]

        for field in klass._meta.fields:

            if field.name not in load_fields:

                skip.add(field.name)

            else:

                init_list.append(field.attname)

            if skip:

        field_count = len(init_list)

        fields = row[index_start : index_start + field_count]

        if fields == (None,) * field_count:

            obj = None

        elif skip:

            klass = deferred_class_factory(klass, skip)

            obj = klass(**dict(zip(init_list, fields)))

        else:

            obj = klass(*fields)

    else:

        field_count = len(klass._meta.fields)

        fields = row[index_start : index_start + field_count]

        if fields == (None,) * field_count:

            obj = None

        else:

            obj = klass(*fields)

    index_end += offset



    index_end = index_start + field_count + offset

    for f in klass._meta.fields:

        if not select_related_descend(f, restricted, requested):

            continue
@@ -948,7 +952,6 @@ def get_cached_row(klass, row, index_start, max_depth=0, cur_depth=0, 
                setattr(obj, f.get_cache_name(), rel_obj)

    return obj, index_end





def delete_objects(seen_objs):

    """

    Iterate through a list of seen classes, and remove any instances that are

tests/regressiontests/defer_regress/models.py

+20 −0
Original line number Diff line number Diff line
@@ -17,6 +17,18 @@ class Item(models.Model): 
class RelatedItem(models.Model):

    item = models.ForeignKey(Item)



class Child(models.Model):

    name = models.CharField(max_length=10)

    value = models.IntegerField()



class Leaf(models.Model):

    name = models.CharField(max_length=10)

    child = models.ForeignKey(Child)

    value = models.IntegerField(default=42)



    def __unicode__(self):

        return self.name



__test__ = {"regression_tests": """

Deferred fields should really be deferred and not accidentally use the field's

default value just because they aren't passed to __init__.
@@ -66,7 +78,15 @@ True 
>>> r.item == i

True



Some further checks for select_related() and inherited model behaviour

(regression for #10710).



>>> c1 = Child.objects.create(name="c1", value=42)

>>> obj = Leaf.objects.create(name="l1", child=c1)



>>> obj = Leaf.objects.only("name", "child").select_related()[0]

>>> obj.child.name

u'c1'



"""

}