public function getDisplayField()
    {
        if ($this->_displayField === null) {
            $schema = $this->getSchema();
            $primary = (array)$this->getPrimaryKey();
            $this->_displayField = array_shift($primary);
            if ($schema->getColumn('title')) {
                $this->_displayField = 'title';
            }
            if ($schema->getColumn('name')) {
                $this->_displayField = 'name';
            }
        }

        return $this->_displayField;
    }