README.md

dict_to_protobuf_to_dict

A python helper library to create a proto object from a dict and also the other way round, i.e, a dict from a proto object. Works against proto3 and handles Maps and filling up of default values in the dict created.

What's handled

• Standard basic scalars, repeated fields, enums, etc.
• Most importantly maps are handled, but with the exception of a map with enum as value ( Will need to figure its handling )
• Getting default values in the proto to dict conversion is handled. Comes handy in our ecosystem as we are not making apps look in the schema to get to know what the type of the field is to decipher the default value. Is particularly handy in case of enums, where we want to get constant 0 label ( the default value )
• Extensions are not handled, as we don't use that in our ecosystem as of now

Example Usage

For a proto schema, named say sample.proto, and having the contents like

syntax = "proto3";

message MyMessage {
  string name = 1;
  repeated string languages_known = 2;
  string favourite_movie = 3;
  map<string, string> degree_college_map = 4;
}

We can generate the python binding by typing the follwing command in the folder where sample.proto is ( can read more on the usage and language guide in general here )

protoc --python_out=.  sample.proto

Once we have generated sample_pb2.py file, we can go about handling messages like

from dict_to_protobuf_to_dict import dict_to_protobuf, protobuf_to_dict
from sample_pb2 import MyMessage

data_dct = {"name": "Neeraj Koul", "languages_known": ["Kashmiri", "Hindi", "English"], 
            "favourite_movie": "The Grapes of Wrath", 
            "degree_college_map": {"B.Tech": "NIT Trichy", "12th": "JK Board"}
            }
message = MyMessage()

# Populate the proto object from the dict
dict_to_protobuf(data_dct, message)

# Serialize proto
proto_serialised_str = message.SerializeToString()

recv_message = MyMessage()
# Deserialize proto
recv_message.ParseFromString(proto_serialised_str)

# Get a dict out
protobuf_to_dict(recv_message)

Tests

Tests are under tests/ folder. To run, we use nosetests

$ nosetests tests/