Fixed #22034 -- Added a specific set of relation checks for GenericInlineModelAdmin.

Thanks to jwa for the report.

2 files changed, 81 insertions, 3 deletions

diff --git a/django/contrib/admin/checks.py b/django/contrib/admin/checks.py
index badc1514cd..dfe4cd04ec 100644
--- a/django/contrib/admin/checks.py
+++ b/django/contrib/admin/checks.py
@@ -846,7 +846,7 @@ class InlineModelAdminChecks(BaseModelAdminChecks):
 
     def check(self, cls, parent_model, **kwargs):
         errors = super(InlineModelAdminChecks, self).check(cls, model=cls.model, **kwargs)
-        errors.extend(self._check_fk_name(cls, parent_model))
+        errors.extend(self._check_relation(cls, parent_model))
         errors.extend(self._check_exclude_of_parent_model(cls, parent_model))
         errors.extend(self._check_extra(cls))
         errors.extend(self._check_max_num(cls))
@@ -861,7 +861,7 @@ class InlineModelAdminChecks(BaseModelAdminChecks):
             return []
 
         # Skip if `fk_name` is invalid.
-        if self._check_fk_name(cls, parent_model):
+        if self._check_relation(cls, parent_model):
             return []
 
         if cls.exclude is None:
@@ -883,7 +883,7 @@ class InlineModelAdminChecks(BaseModelAdminChecks):
         else:
             return []
 
-    def _check_fk_name(self, cls, parent_model):
+    def _check_relation(self, cls, parent_model):
         try:
             _get_foreign_key(parent_model, cls.model, fk_name=cls.fk_name)
         except ValueError as e:
diff --git a/django/contrib/contenttypes/admin.py b/django/contrib/contenttypes/admin.py
index c67fbca288..8da6546a21 100644
--- a/django/contrib/contenttypes/admin.py
+++ b/django/contrib/contenttypes/admin.py
@@ -2,19 +2,97 @@ from __future__ import unicode_literals
 
 from functools import partial
 
+from django.contrib.admin.checks import InlineModelAdminChecks
 from django.contrib.admin.options import InlineModelAdmin, flatten_fieldsets
+from django.contrib.contenttypes.fields import GenericForeignKey
 from django.contrib.contenttypes.forms import (
     BaseGenericInlineFormSet, generic_inlineformset_factory
 )
+from django.core import checks
+from django.db.models.fields import FieldDoesNotExist
 from django.forms import ALL_FIELDS
 from django.forms.models import modelform_defines_fields
 
 
+class GenericInlineModelAdminChecks(InlineModelAdminChecks):
+    def _check_exclude_of_parent_model(self, cls, parent_model):
+        # There's no FK to exclude, so no exclusion checks are required.
+        return []
+
+    def _check_relation(self, cls, parent_model):
+        # There's no FK, but we do need to confirm that the ct_field and ct_fk_field are valid,
+        # and that they are part of a GenericForeignKey.
+
+        gfks = [
+            f for f in cls.model._meta.virtual_fields
+            if isinstance(f, GenericForeignKey)
+        ]
+        if len(gfks) == 0:
+            return [
+                checks.Error(
+                    "'%s.%s' has no GenericForeignKey." % (
+                        cls.model._meta.app_label, cls.model._meta.object_name
+                    ),
+                    hint=None,
+                    obj=cls,
+                    id='admin.E301'
+                )
+            ]
+        else:
+            # Check that the ct_field and ct_fk_fields exist
+            try:
+                cls.model._meta.get_field(cls.ct_field)
+            except FieldDoesNotExist:
+                return [
+                    checks.Error(
+                        "'ct_field' references '%s', which is not a field on '%s.%s'." % (
+                            cls.ct_field, cls.model._meta.app_label, cls.model._meta.object_name
+                        ),
+                        hint=None,
+                        obj=cls,
+                        id='admin.E302'
+                    )
+                ]
+
+            try:
+                cls.model._meta.get_field(cls.ct_fk_field)
+            except FieldDoesNotExist:
+                return [
+                    checks.Error(
+                        "'ct_fk_field' references '%s', which is not a field on '%s.%s'." % (
+                            cls.ct_fk_field, cls.model._meta.app_label, cls.model._meta.object_name
+                        ),
+                        hint=None,
+                        obj=cls,
+                        id='admin.E303'
+                    )
+                ]
+
+            # There's one or more GenericForeignKeys; make sure that one of them
+            # uses the right ct_field and ct_fk_field.
+            for gfk in gfks:
+                if gfk.ct_field == cls.ct_field and gfk.fk_field == cls.ct_fk_field:
+                    return []
+
+            return [
+                checks.Error(
+                    "'%s.%s' has no GenericForeignKey using content type field '%s' and object ID field '%s'." % (
+                        cls.model._meta.app_label, cls.model._meta.object_name, cls.ct_field, cls.ct_fk_field
+                    ),
+                    hint=None,
+                    obj=cls,
+                    id='admin.E304'
+                )
+            ]
+
+
 class GenericInlineModelAdmin(InlineModelAdmin):
     ct_field = "content_type"
     ct_fk_field = "object_id"
     formset = BaseGenericInlineFormSet
 
+    checks_class = GenericInlineModelAdminChecks
+
     def get_formset(self, request, obj=None, **kwargs):
         if 'fields' in kwargs:
             fields = kwargs.pop('fields')