[1.1.X] Restored pre-r10062 behavior allowing None from formfield_callback to exclude itself from the form

Backported from r12891 from trunk

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.1.X@12892 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/forms/models.py

@@ -154,6 +154,7 @@ def fields_for_model(model, fields=None, exclude=None, formfield_callback=lambda
     in the ``fields`` argument.
     """
     field_list = []
+    ignored = []
     opts = model._meta
     for f in opts.fields + opts.many_to_many:
         if not f.editable:
@@ -165,9 +166,14 @@ def fields_for_model(model, fields=None, exclude=None, formfield_callback=lambda
         formfield = formfield_callback(f)
         if formfield:
             field_list.append((f.name, formfield))
+        else:
+            ignored.append(f.name)
     field_dict = SortedDict(field_list)
     if fields:
-        field_dict = SortedDict([(f, field_dict.get(f)) for f in fields if (not exclude) or (exclude and f not in exclude)])
+        field_dict = SortedDict(
+            [(f, field_dict.get(f)) for f in fields
+                if ((not exclude) or (exclude and f not in exclude)) and (f not in ignored)]
+        )
     return field_dict
 
 class ModelFormOptions(object):

tests/modeltests/model_forms/models.py

@@ -205,6 +205,22 @@ class Post(models.Model):
     def __unicode__(self):
         return self.name
 
+class MarkupField(models.CharField):
+    def __init__(self, *args, **kwargs):
+        kwargs["max_length"] = 20
+        super(MarkupField, self).__init__(*args, **kwargs)
+
+    def formfield(self, **kwargs):
+        # don't allow this field to be used in form (real use-case might be
+        # that you know the markup will always be X, but it is among an app
+        # that allows the user to say it could be something else)
+        # regressed at r10062
+        return None
+
+class CustomFieldForExclusionModel(models.Model):
+    name = models.CharField(max_length=10)
+    markup = MarkupField()
+
 __test__ = {'API_TESTS': """
 >>> from django import forms
 >>> from django.forms.models import ModelForm, model_to_dict
@@ -1547,6 +1563,19 @@ False
 >>> f.is_valid()
 True
 
+# Model field that returns None to exclude itself with explicit fields ########
+
+>>> class CustomFieldForExclusionForm(ModelForm):
+...     class Meta:
+...         model = CustomFieldForExclusionModel
+...         fields = ['name', 'markup']
+
+>>> CustomFieldForExclusionForm.base_fields.keys()
+['name']
+
+>>> print CustomFieldForExclusionForm()
+<tr><th><label for="id_name">Name:</label></th><td><input id="id_name" type="text" name="name" maxlength="10" /></td></tr>
+
 # Clean up
 >>> import shutil
 >>> shutil.rmtree(temp_storage_dir)