Support local aliases (close #33).

module/config/services.php

@@ -170,6 +170,33 @@ $container[LeafletServices::ALIAS_GENERATOR] = $container->share(
     }
 );
 
+/**
+ * Leaflet alias generator.
+ *
+ * @return \Netzmacht\Contao\Toolkit\Data\Alias\AliasGenerator
+ */
+$container[LeafletServices::PARENT_ALIAS_GENERATOR] = $container->share(
+    function ($container) {
+        return function ($dataContainerName, $aliasField, $fields) use ($container) {
+            $filters = [
+                new ExistingAliasFilter(),
+                new SlugifyFilter($fields),
+                new DefaultAliasFilter($dataContainerName),
+                new SuffixFilter(),
+            ];
+
+            $validator = new UniqueDatabaseValueValidator(
+                $container[Services::DATABASE_CONNECTION],
+                $dataContainerName,
+                $aliasField,
+                ['pid']
+            );
+
+            return new FilterBasedAliasGenerator($filters, $validator, $dataContainerName, $aliasField, '_');
+        };
+    }
+);
+
 /**
  * Callback helper class for tl_leaflet_map.
  *

module/dca/tl_leaflet_control.php

@@ -22,7 +22,6 @@ $GLOBALS['TL_DCA']['tl_leaflet_control'] = array
             (
                 'id'    => 'primary',
                 'pid'   => 'index',
-                'alias' => 'unique',
             )
         )
     ),
@@ -167,12 +166,12 @@ $GLOBALS['TL_DCA']['tl_leaflet_control'] = array
                     'tl_leaflet_control',
                     'alias',
                     ['title'],
-                    \Netzmacht\Contao\Leaflet\DependencyInjection\LeafletServices::ALIAS_GENERATOR
+                    \Netzmacht\Contao\Leaflet\DependencyInjection\LeafletServices::PARENT_ALIAS_GENERATOR
                 ),
                 \Netzmacht\Contao\Leaflet\Dca\Validator::callback('validateAlias'),
             ),
-            'eval'          => array('mandatory' => false, 'maxlength' => 255, 'tl_class' => 'w50', 'unique' => true),
-            'sql'           => "varchar(255) NOT NULL default ''"
+            'eval'          => array('mandatory' => false, 'maxlength' => 255, 'tl_class' => 'w50', 'nullIfEmpty' => true),
+            'sql'           => "varchar(255) NULL"
         ),
         'type'   => array
         (