[1.4.x] Fixed #14885 - Clarified that ModelForm cleaning may not fully complete if the form is invalid.

Thanks Ben Sturmfels for the patch.

Backport of 3fd89d99036696ba08dd2dd7e20a5b375f85d23b from master.

1 files changed, 7 insertions, 4 deletions

diff --git a/docs/topics/forms/modelforms.txt b/docs/topics/forms/modelforms.txt
index f49c9ba6df..a29da70742 100644
--- a/docs/topics/forms/modelforms.txt
+++ b/docs/topics/forms/modelforms.txt
@@ -200,10 +200,13 @@ The ``is_valid()`` method and ``errors``
 ----------------------------------------
 
 The first time you call ``is_valid()`` or access the ``errors`` attribute of a
-``ModelForm`` triggers form validation as well as :ref:`model validation
-<validating-objects>`. This has the side-effect of cleaning the model you pass
-to the ``ModelForm`` constructor. For instance, calling ``is_valid()`` on your
-form will convert any date fields on your model to actual date objects.
+``ModelForm`` triggers :ref:`form validation <form-and-field-validation>` as
+well as :ref:`model validation <validating-objects>`. This has the side-effect
+of cleaning the model you pass to the ``ModelForm`` constructor. For instance,
+calling ``is_valid()`` on your form will convert any date fields on your model
+to actual date objects. If form validation fails, only some of the updates
+may be applied. For this reason, you'll probably want to avoid reusing the
+model instance.
 
 
 The ``save()`` method