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-rw-r--r--docs/topics/forms/modelforms.txt35
1 files changed, 35 insertions, 0 deletions
diff --git a/docs/topics/forms/modelforms.txt b/docs/topics/forms/modelforms.txt
index add581268b..c5aa9c8a77 100644
--- a/docs/topics/forms/modelforms.txt
+++ b/docs/topics/forms/modelforms.txt
@@ -371,6 +371,35 @@ parameter when declaring the form field::
... class Meta:
... model = Article
+.. note::
+
+ If you explicitly instantiate a form field like this, Django assumes that you
+ want to completely define its behavior; therefore, default attributes (such as
+ ``max_length`` or ``required``) are not drawn from the corresponding model. If
+ you want to maintain the behavior specified in the model, you must set the
+ relevant arguments explicitly when declaring the form field.
+
+ For example, if the ``Article`` model looks like this::
+
+ class Article(models.Model):
+ headline = models.CharField(max_length=200, null=True, blank=True,
+ help_text="Use puns liberally")
+ content = models.TextField()
+
+ and you want to do some custom validation for ``headline``, while keeping
+ the ``blank`` and ``help_text`` values as specified, you might define
+ ``ArticleForm`` like this::
+
+ class ArticleForm(ModelForm):
+ headline = MyFormField(max_length=200, required=False,
+ help_text="Use puns liberally")
+
+ class Meta:
+ model = Article
+
+ See the :ref:`form field documentation <ref-forms-fields>` for more information
+ on fields and their arguments.
+
Changing the order of fields
----------------------------
@@ -512,6 +541,12 @@ Then, pass your ``BaseAuthorFormSet`` class to the factory function::
>>> AuthorFormSet = modelformset_factory(Author, formset=BaseAuthorFormSet)
+If you want to return a formset that doesn't include *any* pre-existing
+instances of the model, you can specify an empty QuerySet::
+
+ >>> AuthorFormSet(queryset=Author.objects.none())
+
+
Controlling which fields are used with ``fields`` and ``exclude``
-----------------------------------------------------------------