protobuf : Optional attributes' values are not cleared

Question

we are currently running a python application that receives json messages, parse it according to the given dict using ParseDict , serialize it SerializeToString and send it.

# encode.py
from google.protobuf.json_format import ParseDict



payload = ParseDict(data, data_t_v1())
raw_payload = payload.SerializeToString()

This what we have in proto file:

//data.proto syntax = "proto2";

message data_t_v1 {
 required uint32 id = 1;
 optional uint32 offset = 2;
 optional uint32 multiplier = 3;
 optional uint32 mask = 4;
 }

However, when I was testing different scenarios, I had an issue concerning the values of optional attributes. Here is what happens:

Test 1- sending the message with the optional values

data = {
"id": 1,
"offset": 2,
"multiplier":10,
"mask": 4294967295 }

Test 2- sending the same message without the optional values

data = {
"id": 1 }

The issue happens here: ParseDict is returning a dict with the optional attributes having the old values that I set in Test 1.

I would like to know if there is a way to clear old optional values when they are not set. Thanks!

Answer 1

Are you create a new instance of your proto message for each test?

from google.protobuf.json_format import ParseDict

# Create a new msg
msg = your_packge_pb2.data_t_v1()

data = {
  "id": 1,
  "offset": 2,
  "multiplier":10,
  "mask": 4294967295,
}

# Parse data into msg
ParseDict(data, msg)

# Do something with msg
print(msg)

# Create a new msg
msg = your_packge_pb2.data_t_v1()

data = {
  "id": 1,
}

# Parse data into msg
ParseDict(data, msg)

# Do something with msg
print(msg)

NOTE The style guide recommends using PascalCase for message names rather than snake_case.