lithium\data\model\Query::schema PHP Method

    public function schema($field = null)
    {
        if (is_object($field)) {
            $this->_schema = $field;
            return;
        }
        if ($schema = $this->_schema) {
            return $field ? $schema[$field] : $schema;
        }
        if ($model = $this->model()) {
            return $model::schema($field);
        } else {
            return $this->_instance('schema');
        }
    }