Changeset 7115

Timestamp:

02/14/08 11:38:05 (5 months ago)

Author:

mtredinnick

Message:

Modified [7112] to make things behave more in line with Python subclassing when subclassing ModelForms?.

Meta can now be subclassed and changes on the child model affect the fields
list. Also removed a block of error checking, since it's harder to mess up in
unexpected ways now (e.g. you can't change the model and get the entirely wrong
fields list), so it was a level of overkill.

Files:

• django/trunk/django/newforms/forms.py (modified) (2 diffs)
• django/trunk/django/newforms/models.py (modified) (2 diffs)
• django/trunk/docs/modelforms.txt (modified) (2 diffs)
• django/trunk/tests/modeltests/model_forms/models.py (modified) (2 diffs)

django/trunk/django/newforms/forms.py

@@ -23 +23 @@
-    return name.replace('_', ' ')
-
-
+
+
+
+
+
+
+
+
+
+
-    fields = [(field_name, attrs.pop(field_name)) for field_name, obj in attrs.items() if isinstance(obj, Field)]
-    fields.sort(lambda x, y: cmp(x[1].creation_counter, y[1].creation_counter))
@@ -30 +39 @@
-    # Note that we loop over the bases in *reverse*. This is necessary in
-    # order to preserve the correct order of fields.
-
-
-
+
+
+
+
+
+
+
+
-
-    return SortedDict(fields)

django/trunk/django/newforms/models.py

@@ -226 +226 @@
-
-        new_class = type.__new__(cls, name, bases, attrs)
-
+, False
-        opts = new_class._meta = ModelFormOptions(getattr(new_class, 'Meta', None))
-        if opts.model:
@@ -237 +237 @@
-        else:
-            fields = declared_fields
+        new_class.declared_fields = declared_fields
-        new_class.base_fields = fields
-
-        # XXX: The following is a sanity check for the user to avoid
-        # inadvertent attribute hiding.
-
-        # Search base classes, but don't allow more than one Meta model
-        # definition. The fields would be generated correctly, but the save
-        # method won't deal with more than one object. Also, it wouldn't be
-        # clear what to do with multiple fields and exclude lists.
-        first = None
-        current = opts.model
-        for base in parents:
-            base_opts = getattr(base, '_meta', None)
-            base_model = getattr(base_opts, 'model', None)
-            if base_model:
-                if current:
-                    if base_model is not current:
-                        raise ImproperlyConfigured("%s's base classes define more than one model." % name)
-                else:
-                    current = base_model
-
-        return new_class
-

django/trunk/docs/modelforms.txt

@@ -336 +336 @@
-is 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 in 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. Most of these won't normally be
-of concern unless you are trying to do something tricky with subclassing.
-
- * All the fields from the parent classes will appear in the child
-   ``ModelForm``. This means you cannot change a parent's ``Meta.exclude``
-   attribute, for example, and except it to have an effect, since the field is
-   already part of the field list in the parent class.
-
- * Normal Python name resolution rules apply. If you have multiple base
@@ -352 +357 @@
-   both a ``ModelForm`` and a ``Form`` simultaneously.
-
-Because of the "child inherits all fields from parents" behaviour, you
-shouldn't try to declare model fields in multiple classes (parent and child).
-Instead, declare all the model-related stuff in one class and use inheritance
-to add "extra" non-model fields and methods to the final result. Whether you
-put the "extra" functions in the parent class or the child class will depend
-on how you intend to reuse them.
-

django/trunk/tests/modeltests/model_forms/models.py

@@ -156 +156 @@
-...         model = Category
-
-
-
-
-
-
-
+
+
+
+
+
+
+
+
-
->>> class ArticleForm(ModelForm):
-...     class Meta:
-...         model = Article
+
+First class with a Meta class wins.
-
->>> class BadForm(ArticleForm, CategoryForm):
-...     pass
-
-
-
-
-
-
-
-
-
-
+
+
-
-Subclassing without specifying a Meta on the class will use the parent's Meta
@@ -186 +182 @@
-...     class Meta:
-...         model = Category
-...         exclude = ['url']
->>> class SubCategoryForm(CategoryForm):
-...     pass
+>>> SubCategoryForm.base_fields.keys()
+['name', 'slug', 'url']
+
+We can also subclass the Meta inner class to change the fields list.
+
+>>> class CategoryForm(ModelForm):
+...     checkbox = forms.BooleanField()
+...
+...     class Meta:
+...         model = Category
+>>> class SubCategoryForm(CategoryForm):
+...     class Meta(CategoryForm.Meta):
+...         exclude = ['url']
-
->>> print SubCategoryForm()
-<tr><th><label for="id_name">Name:</label></th><td><input id="id_name" type="text" name="name" maxlength="20" /></td></tr>
-<tr><th><label for="id_slug">Slug:</label></th><td><input id="id_slug" type="text" name="slug" maxlength="20" /></td></tr>
+<tr><th><label for="id_checkbox">Checkbox:</label></th><td><input type="checkbox" name="checkbox" id="id_checkbox" /></td></tr>
-
-# Old form_for_x tests #######################################################