newforms: Implemented apply_changes() method for form_for_instance Forms

git-svn-id: http://code.djangoproject.com/svn/django/trunk@4253 bcc190cf-cafb-0310-a4f2-bffc1f526a37

2 files changed, 54 insertions, 6 deletions

diff --git a/django/newforms/models.py b/django/newforms/models.py
index 12acc0ac83..e000e394e1 100644
--- a/django/newforms/models.py
+++ b/django/newforms/models.py
@@ -20,6 +20,22 @@ def create(self, save=True):
         obj.save()
     return obj
 
+def make_apply_changes(opts, instance):
+    "Returns the apply_changes() method for a form_for_instance Form."
+    from django.db import models
+    def apply_changes(self, save=True):
+        if self.errors:
+            raise ValueError("The %s could not be changed because the data didn't validate." % opts.object_name)
+        clean_data = self.clean_data
+        for f in opts.fields + opts.many_to_many:
+            if isinstance(f, models.AutoField):
+                continue
+            setattr(instance, f.attname, clean_data[f.name])
+        if save:
+            instance.save()
+        return instance
+    return apply_changes
+
 def form_for_model(model, form=BaseForm):
     """
     Returns a Form class for the given Django model class.
@@ -45,12 +61,13 @@ def form_for_instance(instance, form=BaseForm):
     opts = model._meta
     field_list = []
     for f in opts.fields + opts.many_to_many:
-        current_value = getattr(instance, f.attname)
+        current_value = f.value_from_object(instance)
         formfield = f.formfield(initial=current_value)
         if formfield:
             field_list.append((f.name, formfield))
     fields = SortedDictFromList(field_list)
-    return type(opts.object_name + 'InstanceForm', (form,), {'fields': fields, '_model': model})
+    return type(opts.object_name + 'InstanceForm', (form,),
+        {'fields': fields, '_model': model, 'apply_changes': make_apply_changes(opts, instance)})
 
 def form_for_fields(field_list):
     "Returns a Form class for the given list of Django database field instances."
diff --git a/tests/modeltests/model_forms/models.py b/tests/modeltests/model_forms/models.py
index 8ae9ddc6fb..60a3defde5 100644
--- a/tests/modeltests/model_forms/models.py
+++ b/tests/modeltests/model_forms/models.py
@@ -30,13 +30,14 @@ class Article(models.Model):
     headline = models.CharField(maxlength=50)
     pub_date = models.DateTimeField()
     writer = models.ForeignKey(Writer)
-    categories = models.ManyToManyField(Category)
+    categories = models.ManyToManyField(Category, blank=True)
 
     def __str__(self):
         return self.headline
 
 __test__ = {'API_TESTS': """
 >>> from django.newforms import form_for_model, form_for_instance, BaseForm
+>>> import datetime
 
 >>> Category.objects.all()
 []
@@ -142,12 +143,42 @@ subclass of BaseForm, not Form.
 >>> f.say_hello()
 hello
 
-Use form_for_instance to create a Form from a model instance. The difference
-between this Form and one created via form_for_model is that the object's
-current values are inserted as 'initial' data in each Field.
+Use form_for_instance to create a Form from a model instance. There are two
+differences between this Form and one created via form_for_model. First, the
+object's current values are inserted as 'initial' data in each Field. Second,
+the Form gets an apply_changes() method instead of a create() method.
 >>> w = Writer.objects.get(name='Mike Royko')
 >>> RoykoForm = form_for_instance(w)
 >>> f = RoykoForm(auto_id=False)
 >>> print f
 <tr><th>Name:</th><td><input type="text" name="name" value="Mike Royko" maxlength="50" /></td></tr>
+
+>>> art = Article(headline='Test article', pub_date=datetime.date(1988, 1, 4), writer=w)
+>>> art.save()
+>>> art.id
+1
+>>> TestArticleForm = form_for_instance(art)
+>>> f = TestArticleForm(auto_id=False)
+>>> print f.as_ul()
+<li>Headline: <input type="text" name="headline" value="Test article" maxlength="50" /></li>
+<li>Pub date: <input type="text" name="pub_date" value="1988-01-04" /></li>
+<li>Writer: <select name="writer">
+<option value="">---------</option>
+<option value="1" selected="selected">Mike Royko</option>
+<option value="2">Bob Woodward</option>
+</select></li>
+<li>Categories: <select multiple="multiple" name="categories">
+<option value="1">Entertainment</option>
+<option value="2">It&#39;s a test</option>
+<option value="3">Third test</option>
+</select></li>
+>>> f = TestArticleForm({'headline': u'New headline', 'pub_date': u'1988-01-04', 'writer': u'1'})
+>>> f.is_valid()
+True
+>>> new_art = f.apply_changes()
+>>> new_art.id
+1
+>>> new_art = Article.objects.get(id=1)
+>>> new_art.headline
+'New headline'
 """}