Adapt to new Solr config :

- category -> genre
- cover in solr
- producer -> producerCode

lib/AudioBook.php

@@ -184,9 +184,9 @@ class AudioBook extends DbMapping
     }
 
     /**
-     * Retrieve the list of all categories
+     * Retrieve the list of all genres
      */
-    public static function listOfCategories()
+    public static function ListOfGenres()
     {
         $sql = "SELECT
                     LTRIM(RTRIM(Code)) as code,

lib/BookSearch.php

@@ -25,12 +25,7 @@ class BookSearch
         $this->query = new SolrQuery();
         $this->query->setQuery('*:*');
 
-        $this->query->addField('id');
-        $this->query->addField('title');
-        $this->query->addField('author');
-        $this->query->addField('code');
-        $this->query->addField('category');
-        $this->query->addField('summary');
+        $this->query->addField('*');
 
         $this->query->addParam('q.op', 'AND');
     }