Specify on_delete argument for all related fields that need it

polymorphic/models.py

@@ -37,8 +37,10 @@ class PolymorphicModel(six.with_metaclass(PolymorphicModelBase, models.Model)):
 
     # avoid ContentType related field accessor clash (an error emitted by model validation)
     #: The model field that stores the :class:`~django.contrib.contenttypes.models.ContentType` reference to the actual class.
-    polymorphic_ctype = models.ForeignKey(ContentType, null=True, editable=False,
+    polymorphic_ctype = models.ForeignKey(
-                                          related_name='polymorphic_%(app_label)s.%(class)s_set+')
+        ContentType, null=True, editable=False, on_delete=models.CASCADE,
+        related_name='polymorphic_%(app_label)s.%(class)s_set+'
+    )
 
     # some applications want to know the name of the fields that are added to its models
     polymorphic_internal_model_fields = ['polymorphic_ctype']

polymorphic/tests/__init__.py

@@ -107,7 +107,7 @@ class Enhance_Inherit(Enhance_Base, Enhance_Plain):
 
 class RelationBase(ShowFieldTypeAndContent, PolymorphicModel):
     field_base = models.CharField(max_length=10)
-    fk = models.ForeignKey('self', null=True, related_name='relationbase_set')
+    fk = models.ForeignKey('self', on_delete=models.CASCADE, null=True, related_name='relationbase_set')
     m2m = models.ManyToManyField('self')
 
 
@@ -128,7 +128,7 @@ class RelatingModel(models.Model):
 
 
 class One2OneRelatingModel(PolymorphicModel):
-    one2one = models.OneToOneField(Model2A)
+    one2one = models.OneToOneField(Model2A, on_delete=models.CASCADE)
     field1 = models.CharField(max_length=10)
 
 
@@ -142,7 +142,7 @@ class ModelUnderRelParent(PolymorphicModel):
 
 
 class ModelUnderRelChild(PolymorphicModel):
-    parent = models.ForeignKey(ModelUnderRelParent, related_name='children')
+    parent = models.ForeignKey(ModelUnderRelParent, on_delete=models.CASCADE, related_name='children')
     _private2 = models.CharField(max_length=10)
 
 
@@ -208,7 +208,7 @@ class ParentModelWithManager(PolymorphicModel):
 
 class ChildModelWithManager(PolymorphicModel):
     # Also test whether foreign keys receive the manager:
-    fk = models.ForeignKey(ParentModelWithManager, related_name='childmodel_set')
+    fk = models.ForeignKey(ParentModelWithManager, on_delete=models.CASCADE, related_name='childmodel_set')
     objects = MyManager()
 
 
@@ -232,7 +232,7 @@ class PlainParentModelWithManager(models.Model):
 
 
 class PlainChildModelWithManager(models.Model):
-    fk = models.ForeignKey(PlainParentModelWithManager, related_name='childmodel_set')
+    fk = models.ForeignKey(PlainParentModelWithManager, on_delete=models.CASCADE, related_name='childmodel_set')
     objects = PlainMyManager()
 
 
@@ -264,12 +264,12 @@ class BlogB(BlogBase):
 
 
 class BlogEntry(ShowFieldTypeAndContent, PolymorphicModel):
-    blog = models.ForeignKey(BlogA)
+    blog = models.ForeignKey(BlogA, on_delete=models.CASCADE)
     text = models.CharField(max_length=10)
 
 
 class BlogEntry_limit_choices_to(ShowFieldTypeAndContent, PolymorphicModel):
-    blog = models.ForeignKey(BlogBase)
+    blog = models.ForeignKey(BlogBase, on_delete=models.CASCADE)
     text = models.CharField(max_length=10)
 
 
@@ -375,13 +375,15 @@ class ProxyModelB(ProxyModelBase):
 # with related field 'ContentType.relatednameclash_set'." (reported by Andrew Ingram)
 # fixed with related_name
 class RelatedNameClash(ShowFieldType, PolymorphicModel):
-    ctype = models.ForeignKey(ContentType, null=True, editable=False)
+    ctype = models.ForeignKey(ContentType, on_delete=models.CASCADE, null=True, editable=False)
 
 # class with a parent_link to superclass, and a related_name back to subclass
 
 
 class TestParentLinkAndRelatedName(ModelShow1_plain):
-    superclass = models.OneToOneField(ModelShow1_plain, parent_link=True, related_name='related_name_subclass')
+    superclass = models.OneToOneField(
+        ModelShow1_plain, on_delete=models.CASCADE, parent_link=True, related_name='related_name_subclass'
+    )
 
 
 class CustomPkBase(ShowFieldTypeAndContent, PolymorphicModel):