Return 404 when an ui template cannot be found

app/controllers/ui_controller.rb

@@ -13,28 +13,31 @@
 # limitations under the License.
 
 class UiController < ApplicationController
-  
+  rescue_from ActionView::MissingTemplate do
+    @title = 'Page not found'
+    render :template => "ui/404.html.haml", :status => 404
+  end
+
   def show
     params[:page] ||= "dashboard"
     @id = params[:page].downcase.gsub(/[^a-z]/,'_').squeeze('_')
     @title = params[:page]
-    
+
     respond_to do |format|
       format.html {
         render params[:page].to_sym
       }
     end
   end
-  
-  def visualization
 
+  def visualization
     @id = params[:page].downcase.gsub(/[^a-z]/,'_').squeeze('_')
     @title = params[:page]
-    
+
     respond_to do |format|
       format.html {
         render "ui/visualizations/#{params[:page]}.html.haml"
       }
     end
   end
-end
\ No newline at end of file
+end

app/views/ui/404.html.haml

+- content_for :before_js do
+  %script{:src => relative_path_to("/javascripts/vendor/exhibitv2/exhibit/api/exhibit-api.js")+"?autoCreate=false",
+          :type => "text/javascript"}
+  %script{:src => relative_path_to("/javascripts/lib/exhibit.js"),
+          :type => "text/javascript"}
+
+%h2
+  Page not found

spec/controllers/ui_controller_spec.rb

+# Copyright (c) 2009-2011 Cyril Rohr, INRIA Rennes - Bretagne Atlantique
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+require 'spec_helper'
+
+describe UiController do
+  render_views
+
+  describe "GET /ui/doesnotexist" do
+    it "should return 404 if the page does not exist" do
+      get :visualization, format: :html, params: { :page => 'doesnotexist' }
+      expect(response.status).to eq(404)
+    end
+  end
+end