End-to-End Type-Safe APIs for NestJS

import { Module } from '@nestjs/common';
import { TRPCModule } from 'nestjs-trpc';

@Module({
  imports: [
    TRPCModule.forRoot(),
  ],
})
export class AppModule {}

import { Router, Query } from 'nestjs-trpc';
import { Inject } from '@nestjs/common';
import { z } from 'zod';
import { UserService } from './user.service';

@Router({ alias: 'users' })
export class UserRouter {
  constructor(
    @Inject(UserService)
    private readonly userService: UserService,
  ) {}

  @Query({
    input: z.object({ id: z.string() }),
    output: z.object({
      id: z.string(),
      name: z.string(),
    }),
  })
  getUserById(input: { id: string }) {
    return this.userService.findById(input.id);
  }
}

// Run: npx nestjs-trpc generate

// Client-side usage with full type safety
import { createTRPCClient } from '@trpc/client';
import type { AppRouter } from './server/@generated';

const client = createTRPCClient<AppRouter>({
  links: [/* ... */],
});

// Full autocompletion & type checking
const user = await client.users.getUserById.query({
  id: '1',
});
// ^? { id: string; name: string }