fix handling of errors from param callbacks

fixes #2149

Author: dougwilson

History.md

@@ -1,3 +1,8 @@
+unreleased
+==========
+
+ * fix handling of errors from `router.param()` callbacks
+
 4.3.1 / 2014-05-23
 ==================
 

lib/router/index.js

@@ -290,6 +290,7 @@ proto.process_params = function(layer, called, req, res, done) {
   var key;
   var paramVal;
   var paramCallbacks;
+  var paramCalled;
 
   // process params in order
   // param callbacks can be async
@@ -312,12 +313,18 @@ proto.process_params = function(layer, called, req, res, done) {
     name = key.name;
     paramVal = req.params[name];
     paramCallbacks = params[name];
+    paramCalled = called[name];
 
-    if (paramVal === undefined || !paramCallbacks || called[name] === paramVal) {
+    if (paramVal === undefined || !paramCallbacks) {
       return param();
     }
 
-    called[name] = paramVal;
+    // param previously called with same value or error occurred
+    if (paramCalled && (paramCalled.err || paramCalled.val === paramVal)) {
+      return param(paramCalled.err);
+    }
+
+    called[name] = paramCalled = { val: paramVal };
 
     try {
       return paramCallback();
@@ -328,6 +335,11 @@ proto.process_params = function(layer, called, req, res, done) {
 
   // single param callbacks
   function paramCallback(err) {
+    if (err && paramCalled) {
+      // store error
+      paramCalled.err = err;
+    }
+
     var fn = paramCallbacks[paramIndex++];
     if (err || !fn) return param(err);
     fn(req, res, paramCallback, paramVal, key.name);

test/app.param.js

@@ -194,5 +194,30 @@ describe('app', function(){
       .get('/user/123')
       .expect('name', done);
     })
+
+    it('should defer all the param routes', function(done){
+      var app = express();
+
+      app.param('id', function(req, res, next, val){
+        if (val === 'new') return next('route');
+        return next();
+      });
+
+      app.all('/user/:id', function(req, res){
+        res.send('all.id');
+      });
+
+      app.get('/user/:id', function(req, res){
+        res.send('get.id');
+      });
+
+      app.get('/user/new', function(req, res){
+        res.send('get.new');
+      });
+
+      request(app)
+      .get('/user/new')
+      .expect('get.new', done);
+    })
   })
 })