Use tRPC outside React

“[...] The code easiest to maintain is the code that was never written.”

-- Benjamin Franklin

If you agree, you should try tRPC.

tRPC

tRPC is a library that drastically reduce amount of code you need to write to have a fully typed API Layer.

tRPC can be used with many framework, but a common duo is tRPC and Next.js.

If you write backend code in Next.js projects and use Typescript, give a try to tRPC, because it will make you fly.

Typcal tRPC usage pattern with Next.js

Server side, you create a tRPC router and expose it in a Next.js API route.

Client side, you create a React Hooks that can invoke tRPC router procedures. Then consume the hook in your React Components, in a React Query similar fashion.

But, i need to call tRPC outside React

Many reasons can dictates this:

• You want to call the procedure NOT from a React Component
• Your views implement a cache layer (stored in client), so only if cache is empty you submit the HTTP request
• You use Axios and React Query but you are not ready to replace all React Query hooks with tRPC.useQuery, but you want to replace Axios
• You know ...

In my case i've a cache layer on localStorage and i want only to replace my Axios invocations.

tRPC vanilla client comes into play.

tRPC Vanilla Client

Like Axios is a HTTP client, tRPC Vanilla Client is client used to communicate to tRPC procedures from Vanilla js.

tRPC Vanilla Client let you call your tRPC procedures in the same way as trpc.<procedure-name>.useQuery does.
But unlike trpc.<procedure-name>.useQuery does, you are not limited to use inside React Components/Hooks. You can call it whenever you can call a function that returns a Promise.

Here is how you can replace Axios with it.

// Before
import axios from 'axios';

async function submitFormToServer(formValues: FormValues) {
  console.log('submittin form to server ...');
   try {
    // compose the request DTO
    const dto = {
      title: formValues.title,
      content: formValues.content,
    };
    // submit HTTP request to API Layer
    const response = await axios.post('api/post', dto);

    // parse request result
    if (response.status === 200) {
      console.log('success');
      return { success: true };
    }
    
    throw new Error(); // falltrough catch
  
  } catch (error) {
    console.error('error:', error);
    return { success: false }
  }
}


const Page = () => {
  const handleSubmit = async () => {
    const formValues = ....;
    const {success} = await submitFormToServer(formValues);
    ...
  }
  return <form onSubmit={handleSubmit}>...</form> 
}

// After
import {trpcVanilla} from '../utils/trpc';

async function submitFormToServer(formValues: FormValues) {
  console.log('submittin form to server ...');
   try {
    // submit HTTP request to tRPC API Layer
     await trpcVanilla.createPost.mutate({
      title: formValues.title,
      content: formValues.content,
    });
    return { success: true };
  } catch (error) {
    return { success: false };
  }
}




const Page = () => {
  const handleSubmit = async () => {
    const formValues = ....;
    const {success} = await submitFormToServer(formValues);
    ...
  }
  return <form onSubmit={handleSubmit}>...</form> 
}

How to create tRPC Vanilla Client

View Documentation

Example

// in /utils/trpc.ts

import { createTRPCProxyClient, httpBatchLink } from '@trpc/client';
import type { AppRouter } from '...path to your tRPC router';

export const trpcVanilla = createTRPCProxyClient<AppRouter>({
  links: [
    httpBatchLink({
      url: `http://localhost:3000/api/trpc`,
    }),
  ],
});

Conclusion

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