How to implement the hash method in a protobuf message?

Question

I made a Message.proto file and compiled it to generate python file, named message_pb2. Then in a scenario, I wanted to put my message objects into a set, in order to make them unique. But the __hash__ function of protobuf message raise a TypeError, then I think I can implement and override this function in my code.

I made a new class that inherits message_pb2.Message(), but when running code, I got another error:

KeyError: 'DESCRIPTOR'

Now I don't have any other idea!

Answer 1

I made some changes and use below code, and it worked:

import hashlib
from myproto_pb2 import MyMessage  # Import your generated protobuf message class

class HashableMessage:
    def __init__(self, message):
        self._message = message

    def __hash__(self):
        # Define the fields to include in the hash calculation
        fields_to_hash = [self._message.field1, self._message.field2, self._message.field3]

        # Convert the field values to bytes and concatenate them
        data = b"".join(str(field).encode() for field in fields_to_hash)

        # Calculate the hash value using SHA-256
        hash_value = hashlib.sha256(data).hexdigest()

        return int(hash_value, 16)  # Convert the hex hash to an integer

    def __eq__(self, other):
        return isinstance(other, HashableMessage) and self._message == other._message

# Create a set to store protobuf messages
message_set = set()

# Create an instance of the protobuf message
protobuf_message1 = MyMessage()
protobuf_message1.field1 = "value1"
protobuf_message1.field2 = 42
protobuf_message1.field3 = True


message_set.add(HashableMessage(protobuf_message1))