Always pass the actual request to the data controller.

src/Netzmacht/Contao/Leaflet/Frontend/DataController.php

@@ -58,6 +58,15 @@ class DataController
         $format = $this->getInput('format', 'geojson');
         $type   = $this->getInput('type', 'layer');
         $dataId = $this->getInput('id');
+        $page   = \Input::get('page', true);
+
+        if ($page) {
+            // Fake a page request.
+            \Environment::set('request', base64_decode($page));
+
+            // We need the auto_item being set. So call the getPageIdFromUrl method, this does it internally.
+            \Frontend::getPageIdFromUrl();
+        }
 
         try {
             list($data, $error) = $this->loadData($type, $dataId);

src/Netzmacht/Contao/Leaflet/Frontend/RequestUrl.php

@@ -53,8 +53,25 @@ class RequestUrl
             ->setPath($path)
             ->setQueryParameter('type', $type ?: 'layer')
             ->setQueryParameter('format', $format ?: 'geojson')
-            ->setQueryParameter('id', $dataId);
+            ->setQueryParameter('id', $dataId)
+            ->setQueryParameter('page', rawurlencode(base64_encode(self::getRequestUri())));
 
         return $builder;
     }
+
+    /**
+     * Get the request uri without leading slash.
+     *
+     * @return mixed
+     */
+    protected static function getRequestUri()
+    {
+        $uri = \Environment::get('requestUri');
+
+        if (strpos($uri, '/') === 0) {
+            return substr($uri, 1);
+        }
+
+        return $uri;
+    }
 }