How to create the command object for grpc SubmitRequest in command_submission_service

I want to send the following CreateCommand using python gRPC using command_submission_service. I have imported commands_pb2 How do i define this command…

message CreateCommand {
  // The template of contract the client wants to create.
  // Required
  Identifier template_id = 1;

  // The arguments required for creating a contract from this template.
  // Required
  Record create_arguments = 2;
}

here is the code am currently using

with grpc.insecure_channel('localhost:6865') as channel:
        stub=command_submission_service_pb2_grpc.CommandSubmissionServiceStub(channel)
        response=stub.Submit(command_submission_service_pb2.SubmitRequest(test_command))

basically want to know how to construct test_command. If you have some eg. That would be great

You are broadly looking at something like this:

def run():
    with grpc.insecure_channel('localhost:6865') as channel:
        stub=command_submission_service_pb2_grpc.runSubmissionServiceStub(channel)
        commands=command_submission_service_pb2.Commands()

        commands.application_id="your_daml_user_id"
        commands.command_id=str(uuid.uuid4())
        commands.actAs=["yourpartyid"]

        create_command=command_submission_service_pb2.CreateCommand()
        template_id=command_submission_service_pb2.Identifier()
        template_id.package_id="yourpackageid"
        template_id.module_name="yourmodulename"
        template_id.entity_name="yourtemplatename"

        create_command.template_id=template_id
        payload=command_submission_service_pb2.Record()
        example_field=command_submission_service_pb2.RecordField()
        party_value=command_submission_service_pb2.Value()
        party_value.party="yourpartyid"
        example_field.value =party_value
        payload.fields=[example_field]
        create_command.create_arguments=payload

        commands.commands=[create_command]

        request=command_submission_service_pb2.SubmitRequest()
        request.commands=commands
        response=stub.Submit(command_submission_service_pb2.SubmitRequest())
        print(response)

I don’t have a python environment ready to validate that though.
I recommend to look at the following pieces of documentation:

1. The protobuf docs on how protobuf is translated to python Python Generated Code  |  Protocol Buffers  |  Google Developers
2. The high-level overview of command submission in the ledger API docs The Ledger API Services — Daml SDK 2.4.0 documentation
3. The protobuf docs for the command service Ledger API Reference — Daml SDK 2.4.0 documentation

That said, depending on your usecase dazl may be a significantly easier option to access the grpc API from python.

FWIW I found it quite useful to turn on payload logging, as described in Monitoring — Daml SDK 2.4.2 documentation, when working with gRPC. You can then compare a request that works (say from Navigator) with yours and get an idea of what you need to fix.