tRPC query request won't pass my query parameter

March 5, 2023

Hi when I send request to http://localhost:5000/trpc/test?val=teststring by using below minimal reproducible example, it returns message: "Invalid input: undefined" because as it says, the val really is undefined. What am I doing wrong? I tried to follow the tRPC docs for getting started.

When I sent request to http://localhost:5000/trpc/test?input=teststring, it says, "Unexpected token e in JSON at position 1" in the response. Is sending request like this to tRPC invalid?

index.ts

import express from "express";
import { initTRPC } from "@trpc/server";
import * as trpcExpress from "@trpc/server/adapters/express";

const t = initTRPC.create();
const router = t.router;

export const appRouter = router({
  test: t.procedure
    .input((val: unknown) => {
      console.log({val})
      if (typeof val === 'string') return val;
      throw new Error(`Invalid input: ${typeof val}`);
    })
    .query((req) => {
      const input = req.input;
      return { msg: `You requested: ${input}`};
    }),
});

export type AppRouter = typeof appRouter;

const app = express();
const port = 5000;

app.get("/", (req, res) => {
  res.send("Hello from api-server");
});

app.use(
  "/trpc",
  trpcExpress.createExpressMiddleware({
    router: appRouter,
  })
);
app.listen(port, () => {
  console.log(`api-server listening at http://localhost:${port}`);
});

tsconfig.json

{
  "compilerOptions": {
    "target": "es2016",
    "module": "commonjs",
    "esModuleInterop": true,
    "forceConsistentCasingInFileNames": true,
    "strict": true,
    "skipLibCheck": true
  }
}

package.json

{
  "name": "api-server",
  "version": "1.0.0",
  "license": "MIT",
  "scripts": {
    "start": "ts-node index.ts"
  },
  "dependencies": {
    "@trpc/server": "^10.14.0",
    "express": "^4.17.1",
    "zod": "^3.21.0"
  },
  "devDependencies": {
    "@types/express": "^4.17.13",
    "ts-node": "^10.4.0",
    "typescript": "^4.4.4"
  }
}