Middleware used in a nested router is evaluated on unrelated routes.

Descriptions

The middleware used in a nested-router can be triggered if the regexp matches (matchedRoute) with the unrelated path. The behavior is something intuitive or not easily predictable.

I wrote one router like this, intending to run “checkAuth” middleware when the user accesses to /a/1 or any other subroutes written under /a.

function createAjaxRouter() {
  const router = createRouter('/a');
  router.use(checkAuth);
  router.get('/1', routeHandler(1))
  return router.routes();
}

However, accessing /about (defined elsewhere) can trigger “checkAuth”. This is because middleware is evaluated when the request-path matches /a(.*).

This issue can be avoided by defining the routes /about before this nested router, but manually managing the order of nested routes is difficult.

I wonder if the library can guarantee that middleware used inside the nested-routes are used only in nested routes.

Environment

node.js version: v11.6.0 (Windows) npm/yarn and version: 6.14.5 @koa/router version: 9.0.1 koa version: 2.12.0

Code sample:

const Koa = require('koa');
const Router = require('@koa/router');

function createRouter(prefix) {
  return new Router({
    prefix
  });
}

function routeHandler(x) { 
  return async ctx => {
    console.log(x);
    ctx.body = `${x}`;
  }
}

async function checkAuth(ctx, next) {
  console.log('checkAuth');
  // if (ctx.query['auth'] != "1") {
  //   throw new Error("not authed");
  // }
  await next();
}

function createAjaxRouter() {
  // match for '/a(.*)'
  const router = createRouter('/a');
  router.use(checkAuth);
  router.get('/1', routeHandler(1))
  return router.routes();
}

function createIndexRouter() {
  // match for '(.*)'
  const router = createRouter();
  router.get('/', routeHandler('index'));
  router.get('/about', routeHandler('about'));
  return router.routes();
}

function setRouter(app) {
  // match for '(.*)'
  const router = createRouter();
  router.use(createAjaxRouter());
  router.use(createIndexRouter());

  // order of path in routes.router.stack =>
  // ['/a(.*)', '/a/1', '/', '/about']
  const routes = router.routes();
  app.use(router.routes());
  app.use(router.allowedMethods());
}

const app = new Koa();
setRouter(app);
app.listen(3010); 

Gist

Expected Behavior:

Access to /about should not run the middleware used for nested routes with prefix: /a

Actual Behavior:

Access to /about can trigger the middleware defined in the nested routes.

[julienw]

Looks interesting, thanks for the pointer !

[nightlyherb]

I think #44 is orthogonal to this issue.

That issue is about the Router.used middleware not executing when no paths are matched. In order to solve that one needs to use router.(get|post|...|all) instead.

This issue is about Router.used middleware on “inner router 1” executing on a match in “inner router 2”, which, I suspect, is because there is no “local scope” for the inner routers. (This is what I intended with Item 1, although it doesn’t seem very clear on second read)

Still, thank you for your input.