tRPC Mutation Wait For Data Updated

Question

I'm using tRPC, NextJS, and PyShell for my project. I'll send user input to trpc and use that info as input to python script. Wait for python file done and return updated data to trpc, then send back to frontend.

Currently, it takes longer for python file to finish, and trpc does not send back the right info to frontend. Is there a way to fix that?

The code below is for trpc:

.mutation("upload", {
        // validate input with Zod
        input: z.object({ input: z.string() }).nullish(),
        async resolve({ input }) {
            var msg = ""
            if (input?.input) {
                console.log("-----------------------")

                pyshell.on('message', async function (message) {
                    console.log("MSG: ", message);
                    msg = message;
                });

                pyshell.send(['sent', input.input]).end( function (err) {
                    if (err) console.error(err);
                    console.log("done");
                });
            }
            return msg.length != 0;
        },
    });

msg is supposed to get updated with info from print statement in python file. It shows empty string in msg now.