@remediator/core

⚡ Lightweight frontend mediator for Remix, React Router, Vite & Webpack.

A simple CQRS-style mediator that lets you register handlers and middleware, and dispatch commands or queries with minimal ceremony.

🔧 Install

npm install @remediator/core

📁 Conventions

• Request classes implement IRequest<TResult>
• Handlers implement IRequestHandler<TRequest, TResult>
• Registration pairs a request ctor with its handler via reMediator.register(...)
• Middleware are functions matching (req, ctx, next) => Promise<TResult> and added with reMediator.use(...)

🚀 Setup

Register your handlers and middleware once at app startup (e.g. Remix root, server entry, or React Router loader):

// register handlers
reMediator.register(GetUserQuery, new GetUserQueryHandler());
reMediator.register(UpdateOrderCommand, new UpdateOrderCommandHandler());

// register global middleware (optional)
reMediator.use(authMiddleware);

📡 Dispatching Requests

reMediator.send() has two overloads:

1. Constructor + data: instantiate + hydrate

   await reMediator.send(
     GetUserQuery, // request class
     { id: "u1" }, // partial properties
     request, // raw Request object
     [logMiddleware] // optional per-call middleware
   );

2. Instance: use an existing request object

   const cmd = new UpdateOrderCommand();
   cmd.orderId = "A123";
   cmd.status = "Shipped";
   
   await reMediator.send(
     cmd, // fully-built instance
     request,
     [auditMiddleware] // optional
   );

Both return the handler’s result type.

🛠️ Middleware

Middleware run before the handler and can:

• Examine or modify req fields
• Read/request context via ctx.rawRequest
• Short-circuit or throw errors
• Invoke await next() to continue the pipeline

export const authMiddleware: Pipeline = async (req, ctx, next) => {
  const token = ctx.rawRequest.headers.get("Authorization");
  if (!token) throw new UnauthorizedError();
  ctx.user = verifyToken(token);
  return next();
};

📦 Full Example

// Handler registration
reMediator.register(GetUserQuery, new GetUserQueryHandler());
reMediator.use(authMiddleware);

// In a Remix loader
export async function loader({ request }: LoaderFunctionArgs) {
  // 1) Ctor + data
  const user1 = await reMediator.send(GetUserQuery, { id: "u1" }, request);

  // 2) Instance
  const q = new GetUserQuery();
  q.id = "u2";
  const user2 = await reMediator.send(q, request);

  return json({ user1, user2 });
}

Simple, explicit, and easy to test — perfect for clean frontend CQRS.

© 2025 @remediator/core