Prevent an update of a location when there is a location with the same name.

Fixes #23

src/Hackspace/Bundle/CalciferBundle/Controller/LocationController.php

@@ -143,8 +143,18 @@ class LocationController extends Controller
         }
 
         if ($location->name != $request->get('name')) {
-            $location->name = $request->get('name');
+            // someone changed the name of the location, lets check if the location already exists
-            $location->slug = $location->generateSlug($location->name, $em);
+            $new_location = $repo->findOneBy(['name' => $request->get('name')]);
+            if (is_null($new_location)) {
+                $location->name = $request->get('name');
+                $location->slug = $location->generateSlug($location->name, $em);
+            } else {
+                $request->getSession()->getFlashBag()->add(
+                    'error',
+                    'Ort mit diesem Namen existiert bereits.'
+                );
+                return $this->redirect($this->generateUrl('location_edit', array('slug' => $location->slug)));
+            }
         }
         $location->streetaddress = $request->get('streetaddress');
         $location->streetnumber = $request->get('streetnumber');

src/Hackspace/Bundle/CalciferBundle/Resources/views/Location/edit.html.twig

@@ -29,6 +29,17 @@
         <div class="ui column">
             <form method="post"
                   action="{{ path('location_update',{'slug':entity.slug}) }}">
+                {% set errors = app.session.flashbag.get('error') %}
+                {% if errors|length > 0 %}
+                <div class="ui error message">
+                    <div class="header">Bitte korrigiere folgende Fehler:</div>
+                    <ul class="list">
+                        {% for flashMessage in errors %}
+                        <li>{{ flashMessage }}</li>
+                        {% endfor %}
+                    </ul>
+                </div>
+                {% endif %}
                 <div class="ui form segment">
                     <div class="field">
                         <label class="" for="location-name">Name</label>