Updated python template to read messages with BatchMeta with old version (#1225)

mobs/templates/ee~connectors~msgcodec~msgcodec.py.erb

@@ -7,6 +7,9 @@ import io
 
 class MessageCodec(Codec):
 
+    def __init__(self, msg_selector: List[int] = list()):
+        self.msg_selector = msg_selector
+
     def read_message_id(self, reader: io.BytesIO) -> int:
         """
         Read and return the first byte where the message id is encoded
@@ -46,27 +49,41 @@ class MessageCodec(Codec):
     def decode_detailed(self, b: bytes) -> List[Message]:
         reader = io.BytesIO(b)
         messages_list = list()
+        try:
             messages_list.append(self.handler(reader, 0))
+        except IndexError:
+            print('[WARN] Broken batch')
+            return list()
         if isinstance(messages_list[0], BatchMeta):
             # Old BatchMeta
             mode = 0
         elif isinstance(messages_list[0], BatchMetadata):
             # New BatchMeta
+            if messages_list[0].version == 0:
+                mode = 0
+            else:
                 mode = 1
         else:
             return messages_list
         while True:
             try:
-                messages_list.append(self.handler(reader, mode))
+                msg_decoded = self.handler(reader, mode)
+                if msg_decoded is not None:
+                    messages_list.append(msg_decoded)
             except IndexError:
                 break
         return messages_list
 
     def handler(self, reader: io.BytesIO, mode=0) -> Message:
         message_id = self.read_message_id(reader)
+        #print(f'[INFO-context] Current mode {mode}')
+        #print(f'[INFO] Currently processing message type {message_id}')
         if mode == 1:
-            # We skip the three bytes representing the length of message. It can be used to skip unwanted messages
-            reader.read(3)
+            # We read the three bytes representing the length of message. It can be used to skip unwanted messages
+            r_size = self.read_size(reader)
+            if message_id not in self.msg_selector:
+                reader.read(r_size)
+                return None
             return self.read_head_message(reader, message_id)
         elif mode == 0:
             # Old format with no bytes for message length