Fix to allow $meta projections

mongoframes/frames.py

@@ -638,11 +638,17 @@ def _flatten_projection(cls, projection):
         inclusive = True
         for key, value in deepcopy(projection).items():
             if isinstance(value, dict):
+                # Check for $meta projections
+                if '$meta' in value:
+                    flat_projection[key] = value
+                    continue
+
                 # Store a reference/sub-frame projection
                 if '$ref' in value:
                     references[key] = value
                 elif '$sub' in value or '$sub.' in value:
                     subs[key] = value
+
                 flat_projection[key] = True
 
             elif key == '$ref':
@@ -785,4 +791,4 @@ def _apply_projection(cls, documents, projection):
 
         # Add sub-frames to the documents (if required)
         if subs:
-            Frame._apply_sub_frames(documents, subs)
+            Frame._apply_sub_frames(documents, subs)

setup.py

@@ -21,7 +21,7 @@
     # Versions should comply with PEP440.  For a discussion on single-sourcing
     # the version across setup.py and the project code, see
     # https://packaging.python.org/en/latest/single_source_version.html
-    version='1.2.10',
+    version='1.2.11',
 
     description='A fast unobtrusive MongoDB ODM for Python',
     long_description=long_description,