Issues in compiling grpc python code from protos

Question

I am using python version 2.7.6 and grpcio version 1.12.0. I have a proto with message definition containing a enum something like this

enum Test {
    first 0;
    reserved 1;
    second 2;
}

Now when I try to compile using command

python -m grpc_tools.protoc -I./ --python_out=. --grpc_python_out=. mydata.proto

I get an error message something like this

Missing numeric value for enum constant

Is it because of the python and grpcio version?

Answer 1

Your message definition uses invalid syntax. Perhaps you intend something like:

enum Test {
    first = 0;
    reserved 1;
    second = 2;
}

Note the added equals signs. This enum specifies two values, first and second , and reserves "1" for future use.

Reference:https://developers.google.com/protocol-buffers/docs/proto3#enum

Answer 2

I'll throw an answer on here because this was the top Stack Overflow post when I was getting the same error Missing numeric value for enum constant when I had reserved fields in an enum.

I was trying to compile the headers for C++ and downloaded the protoc compiler that was linked fromthe protocol buffers tutorial . Running Ubuntu 18.04 and just could not get the thing to recognize the reserved fields.

This Github issue was mentioning that I needed to have version 3.6, but I just downloaded and made 3.20 and it still wasn't working.

The issue for me was that I didn't follow the documentation all the way. There is a Readme in the protobuf repo that says, in part:

To build and install the C++ Protocol Buffer runtime and the Protocol Buffer compiler (protoc) execute the following:

 ./configure make -j$(nproc) # $(nproc) ensures it uses all cores for compilation make check sudo make install sudo ldconfig # refresh shared library cache.

I did the ./configure , make , and make check steps, but then forgot to sudo make install or sudo ldconfig . Once I did that, I got the correct version when I ran protoc --version .

I did have an issue where I did all this, got the right version, and then still had errors, but the terminal window I was using had been opened before I installed. Once I ran source ~/.bashrc I was able to build the messages without any issues!