Fixed #21753 -- Raised exception when both `form_class` and `fields` are specified.

1 files changed, 11 insertions, 0 deletions

diff --git a/docs/ref/class-based-views/mixins-editing.txt b/docs/ref/class-based-views/mixins-editing.txt
index 1a06e2bb97..3dcf28dae3 100644
--- a/docs/ref/class-based-views/mixins-editing.txt
+++ b/docs/ref/class-based-views/mixins-editing.txt
@@ -115,6 +115,17 @@ ModelFormMixin
     :attr:`~django.views.generic.detail.SingleObjectMixin.queryset` attributes,
     describing the type of object that the ``ModelForm`` is manipulating.
 
+    If you specify both the
+    :attr:`~django.views.generic.edit.ModelFormMixin.fields` and
+    :attr:`~django.views.generic.edit.FormMixin.form_class` attributes, an
+    :exc:`~django.core.exceptions.ImproperlyConfigured` exception will be
+    raised.
+
+    .. versionchanged:: 1.8
+
+        Previously if both ``fields`` and ``form_class`` were specified,
+        ``fields`` was silently ignored.
+
     **Mixins**
 
     * :class:`django.views.generic.edit.FormMixin`