Use req2params middleware for attributes endpoint

lib/cartodb/controllers/layergroup.js

@@ -67,9 +67,12 @@ LayergroupController.prototype.register = function(app) {
         '/:token/:layer/:z/:x/:y.(:format)', cors(), userMiddleware,
         this.layer.bind(this));
 
-    app.get(app.base_url_mapconfig +
-        '/:token/:layer/attributes/:fid', cors(), userMiddleware,
-        this.attributes.bind(this));
+    app.get(app.base_url_mapconfig + '/:token/:layer/attributes/:fid',
+        cors(),
+        userMiddleware,
+        this.req2paramsMiddleware,
+        this.attributes.bind(this)
+    );
 
     app.get(app.base_url_mapconfig + '/static/center/:token/:z/:lat/:lng/:width/:height.:format',
         cors(),
@@ -223,12 +226,7 @@ LayergroupController.prototype.attributes = function(req, res, next) {
     req.profiler.start('windshaft.maplayer_attribute');
 
     step(
-        function setupParams() {
-            self.req2params(req, res, this);
-        },
-        function retrieveFeatureAttributes(err) {
-            assert.ifError(err);
-
+        function retrieveFeatureAttributes() {
             var mapConfigProvider = new MapStoreMapConfigProvider(
                 self.mapStore, req.context.user, self.userLimitsApi, req.params
             );