public function postUpdate($input)
	{
		$baseModel = $this->getAdmin()->getModel();
		$baseModel = $baseModel::find($this->getAdmin()->getFormBuilder()->getIdentifier());

		$morphType = $baseModel->{$this->getName()}()->getMorphType();
		$morphType = str_replace(sprintf('%s.', $this->getName()), '', $morphType);

		$foreignKey = $baseModel->{$this->getName()}()->getForeignKey();
		$foreignKey = str_replace(sprintf('%s.', $this->getName()), '', $foreignKey);

		// remove old polymorphic relations
		foreach ($baseModel->{$this->getName()} as $item) {
			$item->update([
				$foreignKey => 0,
				$morphType  => '',
			]);
		}

		// update new item with polymorphic relation
		$baseModel->{$this->getName()}()
			->getRelated()
			->where($items->getKeyName(), $input[$this->getName()])
			->update([
				$foreignKey => $this->getAdmin()->getFormBuilder()->getIdentifier(),
				$morphType  => get_class($baseModel),
			]);
	}