protected function getPrimaryName() {
		if ($this->primary === null) {
			$tableModel    = $this->getTableModel();
			$this->primary = $tableModel->getModelsMetaData()->getPrimaryKeyAttributes($tableModel);
			
			if (empty($this->primary)) {
				$this->primary = false;
			}
			
			if (count($this->primary) === 1) {
				$this->primary = current($this->primary);
			}
		}
		
		if ($this->primary === false) {
			return;
		}
		
		return $this->primary;
	}