Invoke default with same arguments as types in res.format

closes #3587

History.md

@@ -5,6 +5,7 @@ unreleased
   * Allow `options` without `filename` in `res.download`
   * Deprecate string and non-integer arguments to `res.status`
   * Ignore `Object.prototype` values in settings through `app.set`/`app.get`
+  * Invoke `default` with same arguments as types in `res.format`
   * Support proper 205 responses using `res.send`
   * deps: [email protected]
     - Remove set content headers that break response

lib/response.js

@@ -684,9 +684,8 @@ res.format = function(obj){
   var req = this.req;
   var next = req.next;
 
-  var fn = obj.default;
-  if (fn) delete obj.default;
-  var keys = Object.keys(obj);
+  var keys = Object.keys(obj)
+    .filter(function (v) { return v !== 'default' })
 
   var key = keys.length > 0
     ? req.accepts(keys)
@@ -697,8 +696,8 @@ res.format = function(obj){
   if (key) {
     this.set('Content-Type', normalizeType(key).value);
     obj[key](req, this, next);
-  } else if (fn) {
-    fn();
+  } else if (obj.default) {
+    obj.default(req, this, next)
   } else {
     var err = new Error('Not Acceptable');
     err.status = err.statusCode = 406;

test/res.format.js

@@ -50,7 +50,12 @@ var app3 = express();
 app3.use(function(req, res, next){
   res.format({
     text: function(){ res.send('hey') },
-    default: function(){ res.send('default') }
+    default: function (a, b, c) {
+      assert(req === a)
+      assert(res === b)
+      assert(next === c)
+      res.send('default')
+    }
   })
 });
 
@@ -118,6 +123,28 @@ describe('res', function(){
         .set('Accept', '*/*')
         .expect('hey', done);
       })
+
+      it('should be able to invoke other formatter', function (done) {
+        var app = express()
+
+        app.use(function (req, res, next) {
+          res.format({
+            json: function () { res.send('json') },
+            default: function () {
+              res.header('x-default', '1')
+              this.json()
+            }
+          })
+        })
+
+        request(app)
+          .get('/')
+          .set('Accept', 'text/plain')
+          .expect(200)
+          .expect('x-default', '1')
+          .expect('json')
+          .end(done)
+      })
     })
 
     describe('in router', function(){