Fixed #21217 -- Avoid connecting `(pre|post)_init` signals to abstract senders.

django/contrib/contenttypes/generic.py

@@ -14,7 +14,7 @@ from django.db.models.fields.related import ForeignObject, ForeignObjectRel
 from django.db.models.related import PathInfo
 from django.db.models.sql.where import Constraint
 from django.forms import ModelForm, ALL_FIELDS
-from django.forms.models import (BaseModelFormSet, modelformset_factory, save_instance,
+from django.forms.models import (BaseModelFormSet, modelformset_factory,
     modelform_defines_fields)
 from django.contrib.admin.options import InlineModelAdmin, flatten_fieldsets
 from django.contrib.contenttypes.models import ContentType
@@ -46,10 +46,10 @@ class GenericForeignKey(six.with_metaclass(RenameGenericForeignKeyMethods)):
         self.cache_attr = "_%s_cache" % name
         cls._meta.add_virtual_field(self)
 
-        # For some reason I don't totally understand, using weakrefs here doesn't work.
-        signals.pre_init.connect(self.instance_pre_init, sender=cls, weak=False)
+        # Only run pre-initialization field assignment on non-abstract models
+        if not cls._meta.abstract:
+            signals.pre_init.connect(self.instance_pre_init, sender=cls)
 
-        # Connect myself as the descriptor for this field
         setattr(cls, name, self)
 
     def instance_pre_init(self, signal, sender, args, kwargs, **_kwargs):

django/db/models/fields/files.py

@@ -358,6 +358,8 @@ class ImageField(FileField):
         # Attach update_dimension_fields so that dimension fields declared
         # after their corresponding image field don't stay cleared by
         # Model.__init__, see bug #11196.
+        # Only run post-initialization dimension update on non-abstract models
+        if not cls._meta.abstract:
             signals.post_init.connect(self.update_dimension_fields, sender=cls)
 
     def update_dimension_fields(self, instance, force=False, *args, **kwargs):

tests/generic_relations/models.py

@@ -32,28 +32,35 @@ class TaggedItem(models.Model):
     def __str__(self):
         return self.tag
 
+
 class ValuableTaggedItem(TaggedItem):
     value = models.PositiveIntegerField()
 
-@python_2_unicode_compatible
-class Comparison(models.Model):
-    """
-    A model that tests having multiple GenericForeignKeys
-    """
+
+class AbstractComparison(models.Model):
     comparative = models.CharField(max_length=50)
 
     content_type1 = models.ForeignKey(ContentType, related_name="comparative1_set")
     object_id1 = models.PositiveIntegerField()
 
+    first_obj = generic.GenericForeignKey(ct_field="content_type1", fk_field="object_id1")
+
+
+@python_2_unicode_compatible
+class Comparison(AbstractComparison):
+    """
+    A model that tests having multiple GenericForeignKeys. One is defined
+    through an inherited abstract model and one defined directly on this class.
+    """
     content_type2 = models.ForeignKey(ContentType, related_name="comparative2_set")
     object_id2 = models.PositiveIntegerField()
 
-    first_obj = generic.GenericForeignKey(ct_field="content_type1", fk_field="object_id1")
     other_obj = generic.GenericForeignKey(ct_field="content_type2", fk_field="object_id2")
 
     def __str__(self):
         return "%s is %s than %s" % (self.first_obj, self.comparative, self.other_obj)
 
+
 @python_2_unicode_compatible
 class Animal(models.Model):
     common_name = models.CharField(max_length=150)
@@ -67,6 +74,7 @@ class Animal(models.Model):
     def __str__(self):
         return self.common_name
 
+
 @python_2_unicode_compatible
 class Vegetable(models.Model):
     name = models.CharField(max_length=150)
@@ -77,6 +85,7 @@ class Vegetable(models.Model):
     def __str__(self):
         return self.name
 
+
 @python_2_unicode_compatible
 class Mineral(models.Model):
     name = models.CharField(max_length=150)
@@ -87,18 +96,22 @@ class Mineral(models.Model):
     def __str__(self):
         return self.name
 
+
 class GeckoManager(models.Manager):
     def get_queryset(self):
         return super(GeckoManager, self).get_queryset().filter(has_tail=True)
 
+
 class Gecko(models.Model):
     has_tail = models.BooleanField(default=False)
     objects = GeckoManager()
 
+
 # To test fix for #11263
 class Rock(Mineral):
     tags = generic.GenericRelation(TaggedItem)
 
+
 class ManualPK(models.Model):
     id = models.IntegerField(primary_key=True)
     tags = generic.GenericRelation(TaggedItem)
@@ -110,14 +123,17 @@ class ForProxyModelModel(models.Model):
     obj = generic.GenericForeignKey(for_concrete_model=False)
     title = models.CharField(max_length=255, null=True)
 
+
 class ForConcreteModelModel(models.Model):
     content_type = models.ForeignKey(ContentType)
     object_id = models.PositiveIntegerField()
     obj = generic.GenericForeignKey()
 
+
 class ConcreteRelatedModel(models.Model):
     bases = generic.GenericRelation(ForProxyModelModel, for_concrete_model=False)
 
+
 class ProxyRelatedModel(ConcreteRelatedModel):
     class Meta:
         proxy = True

tests/model_fields/models.py

@@ -18,13 +18,16 @@ class Foo(models.Model):
     a = models.CharField(max_length=10)
     d = models.DecimalField(max_digits=5, decimal_places=3)
 
+
 def get_foo():
     return Foo.objects.get(id=1)
 
+
 class Bar(models.Model):
     b = models.CharField(max_length=10)
     a = models.ForeignKey(Foo, default=get_foo)
 
+
 class Whiz(models.Model):
     CHOICES = (
         ('Group 1', (
@@ -41,35 +44,44 @@ class Whiz(models.Model):
     )
     c = models.IntegerField(choices=CHOICES, null=True)
 
+
 class BigD(models.Model):
     d = models.DecimalField(max_digits=38, decimal_places=30)
 
+
 class BigS(models.Model):
     s = models.SlugField(max_length=255)
 
+
 class BigInt(models.Model):
     value = models.BigIntegerField()
     null_value = models.BigIntegerField(null=True, blank=True)
 
+
 class Post(models.Model):
     title = models.CharField(max_length=100)
     body = models.TextField()
 
+
 class NullBooleanModel(models.Model):
     nbfield = models.NullBooleanField()
 
+
 class BooleanModel(models.Model):
     bfield = models.BooleanField(default=None)
     string = models.CharField(max_length=10, default='abc')
 
+
 class FksToBooleans(models.Model):
     """Model wih FKs to models with {Null,}BooleanField's, #15040"""
     bf = models.ForeignKey(BooleanModel)
     nbf = models.ForeignKey(NullBooleanModel)
 
+
 class RenamedField(models.Model):
     modelname = models.IntegerField(name="fieldname", choices=((1, 'One'),))
 
+
 class VerboseNameField(models.Model):
     id = models.AutoField("verbose pk", primary_key=True)
     field1 = models.BigIntegerField("verbose field1")
@@ -99,11 +111,13 @@ class VerboseNameField(models.Model):
     field21 = models.TimeField("verbose field21")
     field22 = models.URLField("verbose field22")
 
+
 # This model isn't used in any test, just here to ensure it validates successfully.
 # See ticket #16570.
 class DecimalLessThanOne(models.Model):
     d = models.DecimalField(max_digits=3, decimal_places=3)
 
+
 class DataModel(models.Model):
     short_data = models.BinaryField(max_length=10, default=b'\x08')
     data = models.BinaryField()
@@ -111,6 +125,7 @@ class DataModel(models.Model):
 ###############################################################################
 # FileField
 
+
 class Document(models.Model):
     myfile = models.FileField(upload_to='unused')
 
@@ -127,6 +142,7 @@ if Image:
         def __init__(self, *args, **kwargs):
             self.was_opened = False
             super(TestImageFieldFile, self).__init__(*args, **kwargs)
+
         def open(self):
             self.was_opened = True
             super(TestImageFieldFile, self).open()
@@ -146,15 +162,26 @@ if Image:
         name = models.CharField(max_length=50)
         mugshot = TestImageField(storage=temp_storage, upload_to='tests')
 
-    class PersonWithHeight(models.Model):
+    class AbsctractPersonWithHeight(models.Model):
         """
-        Model that defines an ImageField with only one dimension field.
+        Abstract model that defines an ImageField with only one dimension field
+        to make sure the dimension update is correctly run on concrete subclass
+        instance post-initialization.
         """
-        name = models.CharField(max_length=50)
         mugshot = TestImageField(storage=temp_storage, upload_to='tests',
                                  height_field='mugshot_height')
         mugshot_height = models.PositiveSmallIntegerField()
 
+        class Meta:
+            abstract = True
+
+    class PersonWithHeight(AbsctractPersonWithHeight):
+        """
+        Concrete model that subclass an abctract one with only on dimension
+        field.
+        """
+        name = models.CharField(max_length=50)
+
     class PersonWithHeightAndWidth(models.Model):
         """
         Model that defines height and width fields after the ImageField.

tests/model_fields/test_imagefield.py

@@ -134,7 +134,7 @@ class ImageFieldTests(ImageFieldTestMixin, TestCase):
         p = self.PersonModel.objects.get(name="Joan")
         path = p.mugshot.path
         shutil.move(path, path + '.moved')
-        p2 = self.PersonModel.objects.get(name="Joan")
+        self.PersonModel.objects.get(name="Joan")
 
     def test_delete_when_missing(self):
         """