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https://github.com/lorefnon/ts-json-rpc

Type-safe codegen-free isomorphic RPC solution for Typescript
https://github.com/lorefnon/ts-json-rpc

api nodejs rpc typescript

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Type-safe codegen-free isomorphic RPC solution for Typescript

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README 

        
# ts-json-rpc



Lightweight [JSON-RPC](https://www.jsonrpc.org/specification) solution for TypeScript projects



## Features:



- ðŸ‘Đ‍🔧 Service definition through Zod-based contracts

- 📜 JSON-RPC 2.0 protocol

- ðŸ•ĩïļ Full IDE autocompletion

- ðŸŠķ Tiny footprint (< 1kB)

- 🌎 Support for Deno and edge runtimes

- ðŸšŦ No code generation step



## Basic Usage



Define a shared service contract and export the type of service:



```ts

import { z } from "zod";

import type { ZServiceType } from "@lorefnon/ts-json-rpc/lib/zod";

import { ZService } from "@lorefnon/ts-json-rpc/lib/zod";



export const MyServiceDef = ZService.define({



  hello: z.function()

    .args(z.string())

    .returns(z.string().promise()),



  // More methods here ...

});



export type MyService = ZServiceType

// { hello: (arg: string) => Promise, ... }

```



Define a server-side implementation of this service:



```ts

export const MyServiceImpl = MyServiceDef.implement(() => ({



  async hello(name) { // name is inferred as string

    return `Hello ${name}!`;

  },



  // Implement other methods...

}));

```



Create a server with a route to handle the API requests:



```ts

import express from "express";

import { rpcHandler } from "@lorefnon/ts-json-rpc/lib/express";



const app = express();

app.use(express.json());

app.post("/api", rpcHandler(MyServiceImpl));

app.listen(3000);

```



> **Note**

> You can also use @lorefnon/ts-json-rpc in servers other than Express.

> Check out to docs below for [examples](#support-for-other-runtimes).



On the client-side, import the shared type and create a typed `rpcClient` with it:



```ts

import { rpcClient, HttpPostTransport } from "@lorefnon/ts-json-rpc/lib/client";



// Import the type (not the implementation!)

import type { MyService } from "../shared/MyService";



// Create a typed client:

const client = rpcClient({

  transport: new HttpPostTransport({

    url: "http://localhost:3000/api"

  })

});



// Call a remote method:

console.log(await client.hello("world"));

```



That's all it takes to create a type-safe JSON-RPC API. 🎉



## Demo



You can play with a live example over at StackBlitz:



[![Open in StackBlitz](https://developer.stackblitz.com/img/open_in_stackblitz.svg)](https://stackblitz.com/edit/typed-rpc-express-qeemgh?file=main.ts)



# Advanced Usage



## Service factories vs singletons



It is common for services to be created per request. `DefaultServiceImpl` in above example

is a service factory ie. a function that creates and returns an implementation of the service contract.



rpcHandler will invoke this function for every request to create a service object that handles that particular

request.



This is convenient if you need to access the request (more on this below) but if you don't, instead of a function

you could also create an instance and pass that to rpcHandler:



```ts

app.post("/api", rpcHandler(DefaultServiceImpl({})));

```



Now, we have a singleton service that handles all requests.



## Service context



The function passed to `ServiceDef.implement` can accept a context argument which is available to all the methods.



```ts

interface ServiceContext {

  currentUser?: { name: string }

}



export const MyServiceImpl = ServiceDef.implement((context: ServiceContext) => ({



  async hello() {

    return `Hello ${context.currentUser?.name ?? "Stranger"}!`;

  },



  // Implement other methods...

}));

```



You are responsible for passing this `context` to `DefaultServiceImpl`.



### Accessing the request



Most common use case for context is to get access to the request object.



So, by default rpcHandler will simply pass the request object to service factory as context.



However, if you want to ensure that your service implementation is not tied to a specific server implementation (eg. express) you can also

extract what you need from the request and pass it to the service factory.



```ts

app.post(

  "/api",

  rpcHandler((req) => MyServiceImpl(req.headers))

);

```



This is also useful if you need to inject any additional objects (eg. database pool instance) into the service.



## Support for other runtimes



The generic `@lorefnon/ts-json-rpc/server` package can be used with any server framework or (edge-) runtime.



### Fastify



With [Fastify](https://www.fastify.io/), you would use `@lorefnon/ts-json-rpc` like this:



```ts

import { handleRpc, isJsonRpcRequest } from "@lorefnon/ts-json-rpc/lib/server";



fastify.post("/api", async (req, reply) => {

  if (isJsonRpcRequest(req.body)) {

    const res = await handleRpc(req.body, Service(req));

    reply.send(res);

  }

});

```



## Sending custom headers



A client can send custom request headers by providing a `getHeaders` function:



```ts

const client = rpcClient(apiUrl, {

  getHeaders() {

    return {

      Authorization: auth,

    };

  },

});

```



> **Note**

> The `getHeaders` function can also be `async`.



## CORS credentials



To include credentials in cross-origin requests, pass `credentials: 'include'` as option.



## React hooks



While `@lorefnon/ts-json-rpc` itself does not provide any built-in UI framework integrations,

you can pair it with [react-api-query](https://www.npmjs.com/package/react-api-query),

a thin wrapper around _TanStack Query_. A type-safe match made in heaven. 💕



# License



MIT



# Lineage



This implementation is based on past work by [Felix Gnass](https://indieweb.social/@fgnass)

in [typed-rpc](https://github.com/fgnass/typed-rpc).



The typed-rpc repo is more minimal in its focus (eg. runtime type checking is explicitly not a goal)

and does not appear to be accepting pull requests.