createLocalClient

The createLocalClient function allows you to use your typed API client in a server-side environment (like Next.js Server Components, getServerSideProps, or scripts). Instead of making actual HTTP network requests, it calls your request handlers directly in-memory while preserving the same convenient API and type safety as the browser client.

Usage

You typically create a local client instance alongside your API definition or in a server-only utility file.

server-client.ts

import { createLocalClient } from "@farbenmeer/tapi/server";
import { api } from "./api"; // Your ApiDefinition

export const serverClient = createLocalClient(api);

Then you can use it in your server code:

// app/page.tsx (Server Component)
import { serverClient } from "@/server-client";

export default async function Page() {
  // Calls the handler function directly, no HTTP request involved
  const users = await serverClient.users.get();

  return (
    <ul>
      {users.map(user => <li key={user.id}>{user.name}</li>)}
    </ul>
  );
}

Signature

function createLocalClient<Routes>(
  api: ApiDefinition<Routes>
): Client<Routes>

Parameters

api

Type: ApiDefinition

The API definition object returned by defineApi(). This contains the complete map of your routes and handlers.

How It Works

createLocalClient creates a standard createFetchClient but overrides the internal fetch implementation.

1. It initializes your API using createRequestHandler.
2. When you call a method like .get(), it constructs a Request object representing that call.
3. It passes this request directly to the request handler logic.
4. It parses the returned Response and returns the typed data.

This eliminates the overhead of serialization, network latency, and self-signed certificate issues that can occur when a server tries to fetch from itself via HTTP.

Context Mocking

Since createLocalClient runs inside your server process, the “requests” it generates are synthetic. They will have a base URL of http://localhost.

If your authorize functions or handlers rely on specific headers (like Cookie or Authorization) that would normally come from an incoming browser request, you need to make sure you pass this context explicitly when using the local client:

const headerStore = await headers()
serverClient.users.post({ name: "Milo Mock"}, {
  headers: {
    Authorization: headerStore.get("Authorization")
  }
})