trpc

tRPC End-to-End Typesafe APIs

Instructions

1. Assess the project: tRPC is ideal for full-stack TypeScript monorepos.
2. Follow tRPC conventions:
   • Define routers and procedures
   • Use Zod for input validation
   • Leverage TypeScript inference
   • Integrate with React Query
3. Provide complete examples: Include server routers and client usage.
4. Guide on best practices: Error handling, middleware, subscriptions.

Server Setup

Initialize tRPC

// server/trpc.ts
import { initTRPC, TRPCError } from '@trpc/server';
import { type Context } from './context';
import superjson from 'superjson';

const t = initTRPC.context<Context>().create({
  transformer: superjson,
  errorFormatter({ shape, error }) {
    return {
      ...shape,
      data: {
        ...shape.data,
        zodError: error.cause instanceof ZodError
          ? error.cause.flatten()
          : null,
      },
    };
  },
});

export const router = t.router;
export const publicProcedure = t.procedure;
export const middleware = t.middleware;

Context

// server/context.ts
import { type inferAsyncReturnType } from '@trpc/server';
import { type CreateNextContextOptions } from '@trpc/server/adapters/next';
import { getSession } from 'next-auth/react';
import { prisma } from './db';

export const createContext = async (opts: CreateNextContextOptions) => {
  const session = await getSession({ req: opts.req });

  return {
    session,
    user: session?.user,
    prisma,
  };
};

export type Context = inferAsyncReturnType<typeof createContext>;

Middleware

// server/trpc.ts
const isAuthed = middleware(async ({ ctx, next }) => {
  if (!ctx.session?.user) {
    throw new TRPCError({ code: 'UNAUTHORIZED' });
  }
  return next({
    ctx: {
      ...ctx,
      user: ctx.session.user,
    },
  });
});

const isAdmin = middleware(async ({ ctx, next }) => {
  if (ctx.user?.role !== 'ADMIN') {
    throw new TRPCError({ code: 'FORBIDDEN' });
  }
  return next({ ctx });
});

export const protectedProcedure = t.procedure.use(isAuthed);
export const adminProcedure = t.procedure.use(isAuthed).use(isAdmin);