Merge pull request #3832 from atombrella/warnings_20_fkeys

Regarding #3729

rest_framework/authtoken/models.py

@@ -18,7 +18,8 @@ class Token(models.Model):
     The default authorization token model.
     """
     key = models.CharField(max_length=40, primary_key=True)
-    user = models.OneToOneField(AUTH_USER_MODEL, related_name='auth_token')
+    user = models.OneToOneField(AUTH_USER_MODEL, related_name='auth_token',
+                                on_delete=models.CASCADE)
     created = models.DateTimeField(auto_now_add=True)
 
     def save(self, *args, **kwargs):

tests/models.py

@@ -49,7 +49,8 @@ class ForeignKeyTarget(RESTFrameworkModel):
 class ForeignKeySource(RESTFrameworkModel):
     name = models.CharField(max_length=100)
     target = models.ForeignKey(ForeignKeyTarget, related_name='sources',
-                               help_text='Target', verbose_name='Target')
+                               help_text='Target', verbose_name='Target',
+                               on_delete=models.CASCADE)
 
 
 # Nullable ForeignKey
@@ -57,7 +58,8 @@ class NullableForeignKeySource(RESTFrameworkModel):
     name = models.CharField(max_length=100)
     target = models.ForeignKey(ForeignKeyTarget, null=True, blank=True,
                                related_name='nullable_sources',
-                               verbose_name='Optional target object')
+                               verbose_name='Optional target object',
+                               on_delete=models.CASCADE)
 
 
 # OneToOne
@@ -68,4 +70,4 @@ class OneToOneTarget(RESTFrameworkModel):
 class NullableOneToOneSource(RESTFrameworkModel):
     name = models.CharField(max_length=100)
     target = models.OneToOneField(OneToOneTarget, null=True, blank=True,
-                                  related_name='nullable_source')
+                                  related_name='nullable_source', on_delete=models.CASCADE)