jparise · May 25, 2012 16:25 · May 25, 2012
diff --git a/gistfile1.py b/gistfile1.py
@@ -0,0 +1,45 @@
+class ProtocolBufferMixin(object):
+    """Protocol Buffer support for RequestHandler objects."""
+
+    MIMETYPE = 'application/x-protobuf'
+
+    def read_protobuf(self, message_type, data):
+        """Attempts to parse a protocol buffer message from the given data."""
+        # Create the message object and attempt to parse the data into it.
+        try:
+            message = message_type()
+            if self.request.headers.get('Content-Type') == self.MIMETYPE:
+                message.ParseFromString(data)
+            else:
+                google.protobuf.text_format.Merge(data, message)
+        except Exception, e:
+            logging.error("Failed to parse %s (%d bytes)" %
+                    (message_type.__name__, len(data)), exc_info=True)
+            self.set_status(400)
+            return None
+
+        # Also make sure the message is fully initialized (i.e. all required
+        # fields have been filled out).
+        if not message.IsInitialized():
+            logging.error("Incomplete data for %s (%d bytes)" %
+                    (message_type.__name__, len(data)))
+            self.set_status(400)
+            return None
+
+        # At this point, we have a fully-initialized message object.
+        return message
+
+    def write_protobuf(self, message):
+        """Writes a protocol buffer message to the output buffer.
+
+        If the client's Accept: header advertises support for the protocol
+        buffer MIME type, we write the message in binary form.  Otherwise, we
+        use the protocol buffer text format.
+        """
+        if self.accepts(self.MIMETYPE):
+            self.set_header('Content-Type', self.MIMETYPE)
+            self.write(message.SerializeToString())
+        else:
+            self.set_header('Content-Type', 'text/plain')
+            text = google.protobuf.text_format.MessageToString(message)
+            self.write(text)