Define Routers

Initialize tRPC

tip

• If you don't like the variable name t, you can call it whatever you want
• You should create your root t-variable exactly once per application
• You can also create the t-variable with a context, metadata, a error formatter, or a data transformer.
• It's good to limit the methods you export from the t object in order to constrain your team to use only a few base procedures

server/trpc.ts
ts
import { initTRPC } from '@trpc/server';
 
const t = initTRPC.create();
 
// We explicitly export the methods we use here
// This allows us to create reusable & protected base procedures
export const middleware = t.middleware;
export const router = t.router;
export const publicProcedure = t.procedure;

server/trpc.ts
ts
import { initTRPC } from '@trpc/server';
 
const t = initTRPC.create();
 
// We explicitly export the methods we use here
// This allows us to create reusable & protected base procedures
export const middleware = t.middleware;
export const router = t.router;
export const publicProcedure = t.procedure;

Defining a router

server/_app.ts
ts
import * as trpc from '@trpc/server';
import { publicProcedure, router } from './trpc';
 
const appRouter = router({
  greeting: publicProcedure.query(() => 'hello tRPC v10!'),
});
 
// Export only the **type** of a router to avoid importing server code on the client
export type AppRouter = typeof appRouter;

server/_app.ts
ts
import * as trpc from '@trpc/server';
import { publicProcedure, router } from './trpc';
 
const appRouter = router({
  greeting: publicProcedure.query(() => 'hello tRPC v10!'),
});
 
// Export only the **type** of a router to avoid importing server code on the client
export type AppRouter = typeof appRouter;

initTRPC options

Use chaining to setup your t-object, example:

ts
initTRPC()
  .context<Context>()
  .meta<Meta>()
  .create({ /* [...] */})

ts
initTRPC()
  .context<Context>()
  .meta<Meta>()
  .create({ /* [...] */})

.context<Context>()

Setup a request context.

.meta<Meta>()

Setup metadata for your procedures.

.create(opts: Partial<RuntimeConfig>)

RuntimeConfig reference:

ts
export interface RuntimeConfig<TTypes extends RootConfigTypes> {
  /**
   * Use a data transformer
   * @link https://trpc.io/docs/data-transformers
   */
  transformer: TTypes['transformer'];
  /**
   * Use custom error formatting
   * @link https://trpc.io/docs/error-formatting
   */
  errorFormatter: ErrorFormatter<TTypes['ctx'], any>;
  /**
   * Allow `@trpc/server` to run in non-server environments
   * @warning **Use with caution**, this should likely mainly be used within testing.
   * @default false
   */
  allowOutsideOfServer: boolean;
  /**
   * Is this a server environment?
   * @warning **Use with caution**, this should likely mainly be used within testing.
   * @default typeof window === 'undefined' || 'Deno' in window || process.env.NODE_ENV === 'test'
   */
  isServer: boolean;
  /**
   * Is this development?
   * Will be used to decide if the API should return stack traces
   * @default process.env.NODE_ENV !== 'production'
   */
  isDev: boolean;
}

ts
export interface RuntimeConfig<TTypes extends RootConfigTypes> {
  /**
   * Use a data transformer
   * @link https://trpc.io/docs/data-transformers
   */
  transformer: TTypes['transformer'];
  /**
   * Use custom error formatting
   * @link https://trpc.io/docs/error-formatting
   */
  errorFormatter: ErrorFormatter<TTypes['ctx'], any>;
  /**
   * Allow `@trpc/server` to run in non-server environments
   * @warning **Use with caution**, this should likely mainly be used within testing.
   * @default false
   */
  allowOutsideOfServer: boolean;
  /**
   * Is this a server environment?
   * @warning **Use with caution**, this should likely mainly be used within testing.
   * @default typeof window === 'undefined' || 'Deno' in window || process.env.NODE_ENV === 'test'
   */
  isServer: boolean;
  /**
   * Is this development?
   * Will be used to decide if the API should return stack traces
   * @default process.env.NODE_ENV !== 'production'
   */
  isDev: boolean;
}