Removed fragile admin validation of fields on ModelForm

Refs #19445

django/contrib/admin/options.py

@@ -13,7 +13,7 @@ from django.contrib.admin.util import (unquote, flatten_fieldsets, get_deleted_o
 from django.contrib.admin.templatetags.admin_static import static
 from django.contrib import messages
 from django.views.decorators.csrf import csrf_protect
-from django.core.exceptions import PermissionDenied, ValidationError
+from django.core.exceptions import PermissionDenied, ValidationError, FieldError
 from django.core.paginator import Paginator
 from django.core.urlresolvers import reverse
 from django.db import models, transaction, router
@@ -488,7 +488,11 @@ class ModelAdmin(BaseModelAdmin):
             "formfield_callback": partial(self.formfield_for_dbfield, request=request),
         }
         defaults.update(kwargs)
+        try:
             return modelform_factory(self.model, **defaults)
+        except FieldError as e:
+            raise FieldError('%s. Check fields/fieldsets/exclude attributes of class %s.'
+                             % (e, self.__class__.__name__))
 
     def get_changelist(self, request, **kwargs):
         """

django/contrib/admin/validation.py

@@ -387,15 +387,6 @@ def check_formfield(cls, model, opts, label, field):
         except KeyError:
             raise ImproperlyConfigured("'%s.%s' refers to field '%s' that "
                 "is missing from the form." % (cls.__name__, label, field))
-    else:
-        get_form_is_overridden = hasattr(cls, 'get_form') and cls.get_form != ModelAdmin.get_form
-        if not get_form_is_overridden:
-            fields = fields_for_model(model)
-            try:
-                fields[field]
-            except KeyError:
-                raise ImproperlyConfigured("'%s.%s' refers to field '%s' that "
-                    "is missing from the form." % (cls.__name__, label, field))
 
 def fetch_attr(cls, model, opts, label, field):
     try:

tests/admin_validation/tests.py

@@ -16,10 +16,6 @@ class ValidFields(admin.ModelAdmin):
     form = SongForm
     fields = ['title']
 
-class InvalidFields(admin.ModelAdmin):
-    form = SongForm
-    fields = ['spam']
-
 class ValidFormFieldsets(admin.ModelAdmin):
     def get_form(self, request, obj=None, **kwargs):
         class ExtraFieldForm(SongForm):
@@ -49,10 +45,6 @@ class ValidationTestCase(TestCase):
         # Regression test for #8027: custom ModelForms with fields/fieldsets
         """
         validate(ValidFields, Song)
-        self.assertRaisesMessage(ImproperlyConfigured,
-            "'InvalidFields.fields' refers to field 'spam' that is missing from the form.",
-            validate,
-            InvalidFields, Song)
 
     def test_custom_get_form_with_fieldsets(self):
         """