Server side calls

[samulisuomi]

tRPC supports a concept they call "Server Side Calls", which means you can call the router endpoints inside the same Node process. This would be very useful in ts-rest as well, especially in Next.js – you could define the API logic in one central place, and use the operations not only from the client components over HTTP but also within the server.

I had to test this out, and I'm able to achieve this already by doing this hack in my server component:

// src/app/posts/page.tsx:

import { IncomingHttpHeaders } from 'http'
import { NextApiRequest, NextApiResponse } from 'next'

import postsRouter from '@/api/posts'

export default async function PostsPage() {
  const post = await postsRouter.postGet({
    params: { postId: '5c40e553-414e-4846-bf6b-66dc7f47f48a' },
    headers: {} as IncomingHttpHeaders,
    req: {} as NextApiRequest,
    res: {} as NextApiResponse,
  })

  return (
    <>
      {JSON.stringify((post.body as any)?.post) /* <-- this does correctly print the data! */}
    </>
  )
}

but it would be great to have an official way to do something similar.

Here are the other relevant files for future reference:

// src/api/posts.ts:

const postsRouter = createNextRoute(appApiContract.posts, {
  postGet: async ({ params: { postId } }) => {
    const post = await db
      .selectFrom('posts')
      .select(exposedPostColumns)
      .where('id', '=', postId)
      .executeTakeFirstOrThrow()

    return {
      status: 200,
      body: {
        post,
      },
    }
  },
})

export default postsRouter

// src/pages/api/[...ts-rest].ts

const router = createNextRoute(appApiContract, {
  posts: postsRouter,
})

export default createNextRouter(appApiContract, router, {
  jsonQuery: true,
  responseValidation: true,
})

// src/api/app-api-contract.ts:

const c = initContract()

const appApiContract = c.router({
  posts: c.router({
    postGet: {
      method: 'GET',
      path: '/posts/:postId',
      pathParams: z.object({
        postId: CustomUidSchema,
      }),
      responses: {
        200: z.object({
          post: PostSchema,
        }),
      },
      summary: 'Get a post by ID',
    },
  }),
})

export default appApiContract

This has been an awesome lib so far!

[steschi]

Thanks for sharing this! I am looking for a rest-like tRPC alternative which allows for server side calls from within the same process as well as client side calls from the browser without the need to take care of the transport layer. This looks promising! Wondering if there are clever ways to avoid the type hacking and if there are any caveats.

[dBianchii]

This is a necessary feature imo