Add types middleware

This middleware looks at the list of types that will be sent to
Elasticsearch, if it's an empty array, it sends an error response before
Elasticsearch is even quieried, because Elasticsearch interprets an
empty type array as "search anything" rather than the intended "don't
search anything".

controller/search.js

@@ -1,5 +1,4 @@
 var service = { search: require('../service/search') };
-var types = require ( '../helper/types' );
 
 function setup( backend, query ){
 
@@ -16,11 +15,9 @@ function setup( backend, query ){
       body: query( req.clean )
     };
 
-    // don't directly set cmd.type from types helper to avoid sometimes
-    // setting cmd.type to undefined (having the key not set is cleaner)
-    var type = types(req.clean.types);
-    if (type !== undefined) {
-      cmd.type = type;
+    if (req.clean.type !== undefined) {
+      cmd.type = req.clean.type;
+      delete req.clean.type; // remove type from clean to avoid clutter
     }
 
     // query backend

middleware/_types.js

@@ -0,0 +1,27 @@
+var types_helper = require( '../helper/types' );
+
+/**
+ * Validate the types specified to be searched.
+ *
+ * Elasticsearch interprets an empty array of types as "search anything" rather
+ * than "search nothing", so in the case of an empty array, return an error
+ * message instead of searching at all.
+ */
+function middleware(req, res, next) {
+  var types = types_helper(req.clean.types);
+
+  if (types !== undefined && types.length !== undefined) {
+   if (types.length === 0) {
+    var err = 'You have specified both the `source` and `layers` ' +
+    'parameters in a combination that will return no results.';
+    res.status(400); // 400 Bad Request
+    return next(err);
+   } else {
+     req.clean.type = types;
+   }
+  }
+
+  next();
+}
+
+module.exports = middleware;

routes/v1.js

@@ -9,6 +9,11 @@ var sanitisers = {
   reverse: require('../sanitiser/reverse')
 };
 
+/** ----------------------- middleware ------------------------ **/
+var middleware = {
+  types: require('../middleware/_types')
+};
+
 /** ----------------------- controllers ----------------------- **/
 
 var controllers     = {
@@ -45,6 +50,7 @@ function addRoutes(app, peliasConfig) {
     ]),
     search: createRouter([
       sanitisers.search.middleware,
+      middleware.types,
       controllers.search(),
       postProc.confidenceScores(peliasConfig),
       postProc.renamePlacenames(),

sanitiser/search.js

@@ -4,6 +4,7 @@ var _sanitize = require('../sanitiser/_sanitize'),
       input: require('../sanitiser/_input'),
       size: require('../sanitiser/_size'),
       layers: require('../sanitiser/_layers'),
+      source: require('../sanitiser/_source'),
       details: require('../sanitiser/_details'),
       latlonzoom: require('../sanitiser/_geo')
     };