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Middleware ​

This library supports middleware in multiple ways, and due to how itty-router works, technically any route that doesn't return a response could also be used as middleware.

Per-Route Middleware ​

In each route, you can export a middleware object that contains different middleware functions to use for different methods, or for all methods.

ts
// path: ./src/routes/foo/bar.ts

import type { Middleware, RouteHandler } from "rose";

export const middleware: Middleware = {
  // GET /foo/bar
  GET: (req) => {
    req.ctx["from-middleware"] = "Hello from middleware";
  },
};

// GET /foo/bar
export const GET: RouteHandler = (req) => {
  const middlewareCtx = req.ctx["from-middleware"];

  return new Response(`Middleware Context: '${middlewareCtx}'`);
};
// path: ./src/routes/foo/bar.ts

import type { Middleware, RouteHandler } from "rose";

export const middleware: Middleware = {
  // GET /foo/bar
  GET: (req) => {
    req.ctx["from-middleware"] = "Hello from middleware";
  },
};

// GET /foo/bar
export const GET: RouteHandler = (req) => {
  const middlewareCtx = req.ctx["from-middleware"];

  return new Response(`Middleware Context: '${middlewareCtx}'`);
};

Per-Route-Level Middleware ​

You can also define a middleware function for all paths in a route group and its descendants with an _middleware file.

Like with per-route middleware, you can define the middleware to be for a specific method, or for all methods.

ts
// path: ./src/routes/foo/foo/_middleware.ts

import type { MiddlewareRouteHandler } from "rose";

// GET /foo/*, POST /foo/*, PUT /foo/*, DELETE /foo/*, etc.
export const ALL: MiddlewareRouteHandler = (req) => {
  req.ctx["from-middleware-nested"] = "Context from nested middleware";
};
// path: ./src/routes/foo/foo/_middleware.ts

import type { MiddlewareRouteHandler } from "rose";

// GET /foo/*, POST /foo/*, PUT /foo/*, DELETE /foo/*, etc.
export const ALL: MiddlewareRouteHandler = (req) => {
  req.ctx["from-middleware-nested"] = "Context from nested middleware";
};

Global Middleware ​

To define a global middleware handler, you can create a standard route group-level not found handler that exports the ALL method. This will mean that it catches all requests to any method.

ts
// path: ./src/routes/foo/_middleware.ts

import type { MiddlewareRouteHandler } from "rose";

// GET /*, POST /*, PUT /*, DELETE /*, etc.
export const ALL: MiddlewareRouteHandler = (req) => {
  req.ctx["from-middleware-root"] = "Context from root middleware";
};
// path: ./src/routes/foo/_middleware.ts

import type { MiddlewareRouteHandler } from "rose";

// GET /*, POST /*, PUT /*, DELETE /*, etc.
export const ALL: MiddlewareRouteHandler = (req) => {
  req.ctx["from-middleware-root"] = "Context from root middleware";
};