Client leaflist fix

[ramichael77]

The fix is for proper leaflist parsing and processing.
The 0.8.15 does not have leaflist support.
I failed to use leaflist from main in my project and was forced to fix it.

[akarneliuk]

Is there any testing you can share @ramichael77 ? what is the data you were not able receive and you are able now? also, what about compatibility with previous way?

[ramichael77]

Hi,
Thanks for reviewing!
The val_leaflist support was added in https://github.com/akarneliuk/pygnmi/pull/162/files and was not published in 0.8.15

I tried to use not published https://github.com/akarneliuk/pygnmi/blob/master/pygnmi/client.py#L593C40-L599C100 but immediately failed as the code has the following issue.

1. Problem: Any subitem under leaflist_val is parsed as "json_val" as the hasattr(...) for gRPC is always True:

                                        for e in val_leaflist.leaflist_val.element:
                                            if hasattr(e, "json_val"):        ########## hasattr for gRPC is always True
                                                element_val.update(json.loads(e.json_val))
                                            elif hasattr(e, "json_ietf_val"):   ##########   hasattr for gRPC is always True
                                                element_val.update(json.loads(e.json_ietf_val))
   

The proposed code uses e.HasField(...) and e.ListFields() that are provided by python grpcio grpcio-tools

The all other code uses HasField(...) but not hasattr(...). see for example code below:

# https://github.com/akarneliuk/pygnmi/blob/ccf168a5a80e3611d572cc7bac00ba8600aed47e/pygnmi/client.py#L558
                                    elif update_msg.val.HasField("json_val"):
                                        update_container.update(
                                            {"val": process_potentially_json_value(update_msg.val.json_val)}
                                        )

There is a part of message that I got from our server and the message was parsed by gnmic but not pygnmi:

update {
    path {
      elem {
        ...............  # path was removed 
      }
    }
    val {
      leaflist_val {
        element {
          uint_val: 1434098893918572563
        }
        element {
          uint_val: 13193780073102540425
        }
        element {
          uint_val: 4404749674496952716
        }
        element {
          uint_val: 6951842183180090997
        }
        element {
          uint_val: 4016627188829016379
        }
.............

2. what about compatibility with previous way?
   The previous code was able to parse the "json_val" ONLY as I mentioned above.
   My code permits the "json_val" parsing as well:

                                                if e.HasField("json_val"):
                                                    element_val.append(json.loads(e.json_val))