Create and use getNamedMapProvider middleware

lib/cartodb/controllers/named_maps.js

@@ -27,6 +27,7 @@ NamedMapsController.prototype.register = function(app) {
         cors(),
         userMiddleware,
         this.prepareContext,
+        this.getNamedMapProvider(),
         this.tile.bind(this),
         vectorError()
     );
@@ -37,10 +38,29 @@ NamedMapsController.prototype.register = function(app) {
         userMiddleware,
         allowQueryParams(['layer', 'zoom', 'lon', 'lat', 'bbox']),
         this.prepareContext,
+        this.getNamedMapProvider(),
         this.staticMap.bind(this)
     );
 };
 
+NamedMapsController.prototype.getNamedMapProvider = function () {
+    return function getNamedMapProviderMiddleware (req, res, next) {
+        const { user } = res.locals;
+        const { config, auth_token } = req.query;
+        const { template_id } = req.params;
+
+        this.namedMapProviderCache.get(user, template_id, config, auth_token, res.locals, (err, namedMapProvider) => {
+            if (err) {
+                return next(err);
+            }
+
+            res.locals.namedMapProvider = namedMapProvider;
+
+            next();
+        });
+    }.bind(this);
+};
+
 NamedMapsController.prototype.sendResponse = function(req, res, body, headers, namedMapProvider) {
     this.surrogateKeysCache.tag(res, new NamedMapsCacheEntry(res.locals.user, namedMapProvider.getTemplateName()));
     res.set('Content-Type', headers['content-type'] || headers['Content-Type'] || 'image/png');
@@ -83,23 +103,10 @@ NamedMapsController.prototype.sendResponse = function(req, res, body, headers, n
 NamedMapsController.prototype.tile = function(req, res, next) {
     var self = this;
 
-    var cdbUser = res.locals.user;
+    const { namedMapProvider } = res.locals;
 
-    var namedMapProvider;
     step(
-        function getNamedMapProvider() {
-            self.namedMapProviderCache.get(
-                cdbUser,
-                req.params.template_id,
-                req.query.config,
-                req.query.auth_token,
-                res.locals,
-                this
-            );
-        },
-        function getTile(err, _namedMapProvider) {
-            assert.ifError(err);
-            namedMapProvider = _namedMapProvider;
+        function getTile() {
             self.tileBackend.getTile(namedMapProvider, req.params, this);
         },
         function handleImage(err, tile, headers, stats) {
@@ -126,23 +133,9 @@ NamedMapsController.prototype.staticMap = function(req, res, next) {
     res.locals.format = 'png';
     res.locals.layer = res.locals.layer || 'all';
 
-    var namedMapProvider;
+    const { namedMapProvider } = res.locals;
     step(
-        function getNamedMapProvider() {
-            self.namedMapProviderCache.get(
-                cdbUser,
-                req.params.template_id,
-                req.query.config,
-                req.query.auth_token,
-                res.locals,
-                this
-            );
-        },
-        function prepareLayerVisibility(err, _namedMapProvider) {
-            assert.ifError(err);
-
-            namedMapProvider = _namedMapProvider;
-
+        function prepareLayerVisibility() {
             self.prepareLayerFilterFromPreviewLayers(cdbUser, req, res.locals, namedMapProvider, this);
         },
         function prepareImageOptions(err) {