Changeset 5804

Timestamp:

08/05/07 02:39:36 (2 years ago)

Author:

russellm

Message:

Fixed #4001 -- Added dynamic save_m2m method() to forms created with form_for_model and form_for_instance on save(commit=False).

Files:

• django/trunk/django/newforms/models.py (modified) (2 diffs)
• django/trunk/docs/newforms.txt (modified) (1 diff)
• django/trunk/tests/modeltests/model_forms/models.py (modified) (1 diff)

django/trunk/django/newforms/models.py

@@ -36 +36 @@
-            continue
-        setattr(instance, f.name, cleaned_data[f.name])
-
-
+
+
+
+
-        for f in opts.many_to_many:
-            if fields and f.name not in fields:
@@ -43 +45 @@
-            if f.name in cleaned_data:
-                setattr(instance, f.attname, cleaned_data[f.name])
-
-
-
-
+
+
+
+
+
+
+
+
-    return instance
-

django/trunk/docs/newforms.txt

@@ -1503 +1503 @@
-object before saving it. ``commit`` is ``True`` by default.
-
+Another side effect of using ``commit=False`` is seen when your model has
+a many-to-many relation with another model. If your model has a many-to-many
+relation and you specify ``commit=False`` when you save a form, Django cannot
+immediately save the form data for the many-to-many relation. This is because
+it isn't possible to save many-to-many data for an instance until the instance
+exists in the database.
+
+To work around this problem, every time you save a form using ``commit=False``,
+Django adds a ``save_m2m()`` method to the form created by ``form_for_model``.
+After you have manually saved the instance produced by the form, you can invoke
+``save_m2m()`` to save the many-to-many form data::
+
+    # Create a form instance with POST data.
+    >>> f = AuthorForm(request.POST)
+
+    # Create, but don't save the new author instance
+    >>> new_author = f.save(commit=False)
+
+    # Modify the author in some way
+    ...
+    # Save the new instance
+    >>> new_author.save()
+
+    # Now save the many-to-many data for the form
+    >>> f.save_m2m()
+
+Calling ``save_m2m()`` is only required if you use ``save(commit=False)``.
+When you use a simple ``save()`` on a form, all data - include
+many-to-many data - is saved without the need for any additional method calls.
+
-Using an alternate base class
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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

@@ -332 +332 @@
->>> new_art.categories.all()
-[]
+
+Create a new article, with categories, via the form, but use commit=False.
+The m2m data won't be saved until save_m2m() is invoked on the form.
+>>> ArticleForm = form_for_model(Article)
+>>> f = ArticleForm({'headline': u'The walrus was Paul', 'pub_date': u'1967-11-01',
+...     'writer': u'1', 'article': u'Test.', 'categories': [u'1', u'2']})
+>>> new_art = f.save(commit=False)
+
+# Manually save the instance 
+>>> new_art.save()
+>>> new_art.id
+4
+
+# The instance doesn't have m2m data yet
+>>> new_art = Article.objects.get(id=4)
+>>> new_art.categories.all()
+[]
+
+# Save the m2m data on the form
+>>> f.save_m2m()
+>>> new_art.categories.all()
+[<Category: Entertainment>, <Category: It's a test>]
-
-Here, we define a custom Form. Because it happens to have the same fields as