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

1 files changed, 27 insertions, 10 deletions

diff --git a/django/newforms/forms.py b/django/newforms/forms.py
index 04bf62e445..b4ac80c5aa 100644
--- a/django/newforms/forms.py
+++ b/django/newforms/forms.py
@@ -22,23 +22,40 @@ def pretty_name(name):
     name = name[0].upper() + name[1:]
     return name.replace('_', ' ')
 
-class DeclarativeFieldsMetaclass(type):
+def get_declared_fields(bases, attrs, with_base_fields=True):
     """
-    Metaclass that converts Field attributes to a dictionary called
-    'base_fields', taking into account parent class 'base_fields' as well.
+    Create a list of form field instances from the passed in 'attrs', plus any
+    similar fields on the base classes (in 'bases'). This is used by both the
+    Form and ModelForm metclasses.
+
+    If 'with_base_fields' is True, all fields from the bases are used.
+    Otherwise, only fields in the 'declared_fields' attribute on the bases are
+    used. The distinction is useful in ModelForm subclassing.
     """
-    def __new__(cls, name, bases, attrs):
-        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))
+    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))
 
-        # If this class is subclassing another Form, add that Form's fields.
-        # Note that we loop over the bases in *reverse*. This is necessary in
-        # order to preserve the correct order of fields.
+    # If this class is subclassing another Form, add that Form's fields.
+    # Note that we loop over the bases in *reverse*. This is necessary in
+    # order to preserve the correct order of fields.
+    if with_base_fields:
         for base in bases[::-1]:
             if hasattr(base, 'base_fields'):
                 fields = base.base_fields.items() + fields
+    else:
+        for base in bases[::-1]:
+            if hasattr(base, 'declared_fields'):
+                fields = base.declared_fields.items() + fields
+
+    return SortedDict(fields)
 
-        attrs['base_fields'] = SortedDict(fields)
+class DeclarativeFieldsMetaclass(type):
+    """
+    Metaclass that converts Field attributes to a dictionary called
+    'base_fields', taking into account parent class 'base_fields' as well.
+    """
+    def __new__(cls, name, bases, attrs):
+        attrs['base_fields'] = get_declared_fields(bases, attrs)
         return type.__new__(cls, name, bases, attrs)
 
 class BaseForm(StrAndUnicode):