Repository.php

    /**
     * @param array $filter
     * @param array $fields
     * @return array
     */
    public function getFilterInfo($filter = array(),$fields = array()){
        /**
         * Formats the fields
         */
        $statementFields = array();
        foreach($fields as $f){
            $statementFields[] = "MIN({$f})";
            $statementFields[] = "MAX({$f})";
            unset($f);
        }
        $statementFields = implode(",",$statementFields);

        /**
         * Gets a query object matching my filter
         */
        $query = $this->getFilterQuery($filter);

        /**
         * Runs a custom statement on the query
         */
        $query->statement("SELECT ? FROM tx_nimcarshop_domain_model_usedcar",array($statementFields));

        /**
         * Returns an array
         */
        return $query->execute(true);
    }