useQuery() (v9)

The hooks provided by @trpc/react are a thin wrapper around React Query. For in-depth information about options and usage patterns, refer to their docs on Queries.

function useQuery(
  pathAndInput: [string, TInput?],
  opts?: UseTRPCQueryOptions;
)

The first argument is a [path, input]-tuple - if the input is optional, you can omit the , input-part.

You'll notice that you get autocompletion on the path and automatic typesafety on the input.

Example

Backend code

server/routers/_app.ts

import * as trpc from '@trpc/server';
import { z } from 'zod';

export const appRouter = trpc
  .router()
  // Create procedure at path 'hello'
  .query('hello', {
    // using zod schema to validate and infer input values
    input: z
      .object({
        text: z.string().nullish(),
      })
      .nullish(),
    resolve({ input }) {
      return {
        greeting: `hello ${input?.text ?? 'world'}`,
      };
    },
  });

components/MyComponent.tsx

import { trpc } from '../utils/trpc';

export function MyComponent() {
  // input is optional, so we don't have to pass second argument
  const helloNoArgs = trpc.useQuery(['hello']);
  const helloWithArgs = trpc.useQuery(['hello', { text: 'client' }]);

  return (
    <div>
      <h1>Hello World Example</h1>
      <ul>
        <li>
          helloNoArgs ({helloNoArgs.status}):{' '}
          <pre>{JSON.stringify(helloNoArgs.data, null, 2)}</pre>
        </li>
        <li>
          helloWithArgs ({helloWithArgs.status}):{' '}
          <pre>{JSON.stringify(helloWithArgs.data, null, 2)}</pre>
        </li>
      </ul>
    </div>
  );
}