Added a Django storage backend.

- New GridFSStorage storage backend
- New FileDocument document for storing files in GridFS
- Whitespace cleaned up in various files

mongoengine/base.py

@@ -23,7 +23,7 @@ class BaseField(object):
     # Fields may have _types inserted into indexes by default 
     _index_with_types = True
     _geo_index = False
-    
+
     def __init__(self, db_field=None, name=None, required=False, default=None, 
                  unique=False, unique_with=None, primary_key=False,
                  validation=None, choices=None):
@@ -89,7 +89,7 @@ class BaseField(object):
             if value not in self.choices:
                 raise ValidationError("Value must be one of %s."
                     % unicode(self.choices))
-        
+
         # check validation argument
         if self.validation is not None:
             if callable(self.validation):
@@ -98,13 +98,13 @@ class BaseField(object):
                                           'validation method.')
             else:
                 raise ValueError('validation argument must be a callable.')
-    
+
         self.validate(value)
 
 class ObjectIdField(BaseField):
     """An field wrapper around MongoDB's ObjectIds.
     """
-    
+
     def to_python(self, value):
         return value
         # return unicode(value)
@@ -150,7 +150,7 @@ class DocumentMetaclass(type):
                 # Get superclasses from superclass
                 superclasses[base._class_name] = base
                 superclasses.update(base._superclasses)
-                
+
             if hasattr(base, '_meta'):
                 # Ensure that the Document class may be subclassed - 
                 # inheritance may be disabled to remove dependency on 
@@ -191,20 +191,20 @@ class DocumentMetaclass(type):
             field.owner_document = new_class
 
         module = attrs.get('__module__')
-        
+
         base_excs = tuple(base.DoesNotExist for base in bases 
                           if hasattr(base, 'DoesNotExist')) or (DoesNotExist,)
         exc = subclass_exception('DoesNotExist', base_excs, module)
         new_class.add_to_class('DoesNotExist', exc)
-        
+
         base_excs = tuple(base.MultipleObjectsReturned for base in bases 
                           if hasattr(base, 'MultipleObjectsReturned'))
         base_excs = base_excs or (MultipleObjectsReturned,)
         exc = subclass_exception('MultipleObjectsReturned', base_excs, module)
         new_class.add_to_class('MultipleObjectsReturned', exc)
-    
+
         return new_class
-        
+
     def add_to_class(self, name, value):
         setattr(self, name, value)
 
@@ -227,7 +227,7 @@ class TopLevelDocumentMetaclass(DocumentMetaclass):
             return super_new(cls, name, bases, attrs)
 
         collection = name.lower()
-        
+
         id_field = None
         base_indexes = []
         base_meta = {}
@@ -265,7 +265,7 @@ class TopLevelDocumentMetaclass(DocumentMetaclass):
         # Set up collection manager, needs the class to have fields so use
         # DocumentMetaclass before instantiating CollectionManager object
         new_class = super_new(cls, name, bases, attrs)
-        
+
         # Provide a default queryset unless one has been manually provided
         if not hasattr(new_class, 'objects'):
             new_class.objects = QuerySetManager()
@@ -273,7 +273,7 @@ class TopLevelDocumentMetaclass(DocumentMetaclass):
         user_indexes = [QuerySet._build_index_spec(new_class, spec)
                         for spec in meta['indexes']] + base_indexes
         new_class._meta['indexes'] = user_indexes
-        
+
         unique_indexes = []
         for field_name, field in new_class._fields.items():
             # Generate a list of indexes needed by uniqueness constraints
@@ -431,7 +431,7 @@ class BaseDocument(object):
         if data.has_key('_id') and not data['_id']:
             del data['_id']
         return data
-    
+
     @classmethod
     def _from_son(cls, son):
         """Create an instance of a Document (subclass) from a PyMongo SON.
@@ -468,7 +468,7 @@ class BaseDocument(object):
         obj = cls(**data)
         obj._present_fields = present_fields
         return obj
-    
+
     def __eq__(self, other):
         if isinstance(other, self.__class__) and hasattr(other, 'id'):
             if self.id == other.id: