How To Fix: TypeError: No positional arguments allowed' in python List object with gRPC

Question

I have already looked at this post, which doesn't answer my problem

Here is how my proto file looks like

message GetWarehousesRequest {
  CreateAttributes base_wh = 1;
  repeated CreateAttributes partnered_wh = 2;
}

(i am not posting grpc method signatures because they are trivial)

Note how partnered_wh is an array.

In python i have this method

    def get_warehouses(
        self,
        base_wh: create_attributes_pb2,
        partnered_whs: List[create_attributes_pb2],
    ) -> int:
        start_time = utcnow().replace(tzinfo=None)
        request = get_warehouses_request_pb2(
            base_wh=base_wh,
        )

        for partnered_wh in partnered_whs:
            request.partnered_wh.add(partnered_wh)

In the for loop i am getting error that No position arguments are allowed. I need to convert python List to gRPC array. What should be best way to do so? Can i just assign that list to object? or there is better way?

Answer 1

You have 3 options:

1. c = p.add() -- adds a new child and returns (!) it
2. `p.append(c) -- appends a child
3. `p.extend([c1,..cn]) -- appends multiple children

Assuming create_attributes.proto:

syntax = "proto3";

message CreateAttributes {}

message GetWarehousesRequest {
  CreateAttributes base_wh = 1;
  repeated CreateAttributes partnered_wh = 2;
}

And:

protoc \
--proto_path=${PWD} \
--python_out=${PWD} \
--pyi_out=${PWD} \
${PWD}/create_attributes.proto 

Then:

import create_attributes_pb2
import datetime

def get_warehouses(
  self,
  base_wh: create_attributes_pb2.CreateAttributes,
  partnered_whs: List[create_attributes_pb2.CreateAttributes],
) -> int:
  start_time = datetime.datetime.utcnow().replace(tzinfo=None)
  request =create_attributes_pb2.GetWarehousesRequest(
    base_wh=base_wh,
  )

  # You can append the list (!) using `extend`
  request.partnered_wh.extend(partnered_whs)

  return(1)

Demonstrating each method (1..3):

import create_attributes_pb2


gwr = create_attributes_pb2.GetWarehousesRequest()

# 1 `add` adds a new and returns a CreateAttributes (ca1)
ca1 = gwr.partnered_wh.add()
assert(type(ca1) == create_attributes_pb2.CreateAttributes)

# 2 `append` adds an existing CreateAttributes (ca2)
ca2 = create_attributes_pb2.CreateAttributes()
gwr.partnered_wh.append(ca2)

# 3 `extends` adds a list of existing CreateAttributes
ca3 = create_attributes_pb2.CreateAttributes()
ca4 = create_attributes_pb2.CreateAttributes()
gwr.partnered_wh.extend([ca3,ca4])

print(gwr)