From 2d0588548e52c78e5213d262a5c4e5df1da3450e Mon Sep 17 00:00:00 2001 From: Malcolm Tredinnick Date: Sat, 16 Feb 2008 06:57:52 +0000 Subject: queryset-refactor: Merged from trunk up to [7122]. git-svn-id: http://code.djangoproject.com/svn/django/branches/queryset-refactor@7124 bcc190cf-cafb-0310-a4f2-bffc1f526a37 --- docs/modelforms.txt | 38 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+) (limited to 'docs/modelforms.txt') diff --git a/docs/modelforms.txt b/docs/modelforms.txt index a99e27fff7..853fb3159e 100644 --- a/docs/modelforms.txt +++ b/docs/modelforms.txt @@ -320,3 +320,41 @@ parameter when declaring the form field:: ... ... class Meta: ... model = Article + +Form inheritance +---------------- + +As with basic forms, you can extend and reuse ``ModelForms`` by inheriting +them. This is useful if you need to declare extra fields or extra methods on a +parent class for use in a number of forms derived from models. For example, +using the previous ``ArticleForm`` class:: + + >>> class EnhancedArticleForm(ArticleForm): + ... def clean_pub_date(self): + ... ... + +This creates a form that behaves identically to ``ArticleForm``, except there's +some extra validation and cleaning for the ``pub_date`` field. + +You can also subclass the parent's ``Meta`` inner class if you want to change +the ``Meta.fields`` or ``Meta.excludes`` lists:: + + >>> class RestrictedArticleForm(EnhancedArticleForm): + ... class Meta(ArticleForm.Meta): + ... exclude = ['body'] + +This adds the extra method from the ``EnhancedArticleForm`` and modifies +the original ``ArticleForm.Meta`` to remove one field. + +There are a couple of things to note, however. + + * Normal Python name resolution rules apply. If you have multiple base + classes that declare a ``Meta`` inner class, only the first one will be + used. This means the child's ``Meta``, if it exists, otherwise the + ``Meta`` of the first parent, etc. + + * For technical reasons, a subclass cannot inherit from both a ``ModelForm`` + and a ``Form`` simultaneously. + +Chances are these notes won't affect you unless you're trying to do something +tricky with subclassing. -- cgit v1.3