CodeIgniter/Datamapper - 更新一对多关系
与 CodeIgniter/Datamapper 更新一对多关系时遇到问题。在我的脑海中，我有这样一个想法：一对多关系何时更新。关系表中的现有记录将被删除，并添加新的关系。事实似乎并非如此。
使用以下内容，每次都会向关系表添加新记录：
$item->save($banners);
创建的关系是正确的，但我期望关系表中仅包含 $banners 中包含的对象，而不是任何历史项。
这是正确的功能吗？如果是，使此更新过程正常工作的最佳方法是什么？
谢谢
Having an issue with update one-to-many relationships with CodeIgniter/Datamapper. In my mind I had the notion that when a one-to-many relationship was updated. The existing records within the relationship table would be removed and the new relationships added. This appears not to be the case.
Using the following, adds new records to the relationship table each time:
$item->save($banners);
The relationships that are created are correct but I was expecting only the objects contained within $banners to be included in the relationship table not any historial items.
Is this correct functionality and if so what is the best method for making this update process work?
Thanks
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一对多并不意味着“只有一个可以关联”。请参阅 维基百科
它只是意味着关系的“一”方包含外部钥匙。
如果您想要此行为，您需要手动重置现有关系。使用更新查询速度最快，其中将“foreign_key”设置为 NULL，其中“foreign_key”是要关联的对象的“id”值。
One-to-many doesn't mean "only one can be related". See Wikipedia
It just means that the "one" side of the relationship contains the foreign key.
You need to manually reset existing relations if you want this behaviour. This goes quickest using an update query where you set 'foreign_key' to NULL where 'foreign_key' is the 'id' value of the object to be related.