Support mounted app as any argument to app.use()

fixes #2277

History.md

@@ -5,6 +5,7 @@ unreleased
     - accepts a file system path instead of a URL
     - requires an absolute path or `root` option specified
   * deprecate `res.sendfile` -- use `res.sendFile` instead
+  * support mounted app as any argument to `app.use()`
   * deps: qs@1.0.2
     - Complete rewrite
     - Limits array length to 20

lib/application.js

@@ -3,6 +3,7 @@
  */
 
 var finalhandler = require('finalhandler');
+var flatten = require('./utils').flatten;
 var mixin = require('utils-merge');
 var Router = require('./router');
 var methods = require('methods');
@@ -16,6 +17,7 @@ var compileQueryParser = require('./utils').compileQueryParser;
 var compileTrust = require('./utils').compileTrust;
 var deprecate = require('depd')('express');
 var resolve = require('path').resolve;
+var slice = Array.prototype.slice;
 
 /**
  * Application prototype.
@@ -149,34 +151,41 @@ app.handle = function(req, res, done) {
  * @api public
  */
 
-app.use = function use(path, fn) {
-  var mount_app;
-  var mount_path;
+app.use = function use(fn) {
+  var offset = 0;
+  var path = '/';
+  var self = this;
 
-  // check for .use(path, app) or .use(app) signature
-  if (arguments.length <= 2) {
-    mount_path = typeof path === 'string'
-      ? path
-      : '/';
-    mount_app = typeof path === 'function'
-      ? path
-      : fn;
+  // default path to '/'
+  if (typeof fn !== 'function') {
+    offset = 1;
+    path = fn;
+  }
+
+  var fns = flatten(slice.call(arguments, offset));
+
+  if (fns.length === 0) {
+    throw new TypeError('app.use() requires middleware functions');
   }
 
   // setup router
   this.lazyrouter();
   var router = this._router;
 
-  // express app
-  if (mount_app && mount_app.handle && mount_app.set) {
-    debug('.use app under %s', mount_path);
-    mount_app.mountpath = mount_path;
-    mount_app.parent = this;
+  fns.forEach(function (fn) {
+    // non-express app
+    if (!fn || !fn.handle || !fn.set) {
+      return router.use(path, fn);
+    }
+
+    debug('.use app under %s', path);
+    fn.mountpath = path;
+    fn.parent = self;
 
     // restore .app property on req and res
-    router.use(mount_path, function mounted_app(req, res, next) {
+    router.use(path, function mounted_app(req, res, next) {
       var orig = req.app;
-      mount_app.handle(req, res, function(err) {
+      fn.handle(req, res, function (err) {
         req.__proto__ = orig.request;
         res.__proto__ = orig.response;
         next(err);
@@ -184,13 +193,8 @@ app.use = function use(path, fn) {
     });
 
     // mounted an app
-    mount_app.emit('mount', this);
-
-    return this;
-  }
-
-  // pass-through use
-  router.use.apply(router, arguments);
+    fn.emit('mount', self);
+  });
 
   return this;
 };
@@ -414,7 +418,7 @@ methods.forEach(function(method){
     this.lazyrouter();
 
     var route = this._router.route(path);
-    route[method].apply(route, [].slice.call(arguments, 1));
+    route[method].apply(route, slice.call(arguments, 1));
     return this;
   };
 });
@@ -433,7 +437,7 @@ app.all = function(path){
   this.lazyrouter();
 
   var route = this._router.route(path);
-  var args = [].slice.call(arguments, 1);
+  var args = slice.call(arguments, 1);
   methods.forEach(function(method){
     route[method].apply(route, args);
   });

test/app.use.js

@@ -18,7 +18,7 @@ describe('app', function(){
 
   it('should reject missing functions', function(){
     var app = express();
-    app.use.bind(app, 3).should.throw(/requires callback function/);
+    app.use.bind(app, 3).should.throw(/requires middleware function/);
   })
 
   describe('.use(app)', function(){
@@ -84,6 +84,44 @@ describe('app', function(){
       .get('/post/once-upon-a-time')
       .expect('success', done);
     })
+
+    it('should support mounted app anywhere', function(done){
+      var cb = after(3, done);
+      var blog = express()
+        , other = express()
+        , app = express();
+
+      function fn1(req, res, next) {
+        res.setHeader('x-fn-1', 'hit');
+        next();
+      }
+
+      function fn2(req, res, next) {
+        res.setHeader('x-fn-2', 'hit');
+        next();
+      }
+
+      blog.get('/', function(req, res){
+        res.end('success');
+      });
+
+      blog.once('mount', function (parent) {
+        parent.should.equal(app);
+        cb();
+      });
+      other.once('mount', function (parent) {
+        parent.should.equal(app);
+        cb();
+      });
+
+      app.use('/post/:article', fn1, other, fn2, blog);
+
+      request(app)
+      .get('/post/once-upon-a-time')
+      .expect('x-fn-1', 'hit')
+      .expect('x-fn-2', 'hit')
+      .expect('success', cb);
+    })
   })
 
   describe('.use(middleware)', function(){