Doctrine2更新关系多对多（没有Symfony）

I have 2 Doctrine Entities with many-to-many relations. When I edit the first entity I want to be able to select the checkboxes that have the data from the 2nd entity to establish the joins for particular entry.

It works fine on creating a new Entry (using Array Collection), but when I want to edit an Entry - it adds the ones that I have selected without removing the previous choice (unchecking).

Which way would be the correct way to do that and how?

1. Remove all the Join table data for the Entry that is being updated, then set the new data. (How can I remove it from the join table that is not an Entity?)
2. Pass all the data from the 2nd Entity and remove those that aren't checked (seems super-clumsy?)
3. Some other way I am not aware of?

I am not using Symfony, just Doctrine.

Doctrine makes working with the many-to-many associations quite easy. Your associations are stored into an ArrayCollection class that has some methods that can help you. First of all, check all the available methods for the ArrayCollection here (Doctrine API - ArrayCollection)

In your case, I'd use this approach: use the clear method on your ArrayCollection that contains the relationship with the 2nd entity and populate it again with the checked elements. After this, call the flush method on the entitymanager.

Another approach consists in filtering your collection (with the filter method) for getting a brand new ArrayCollection that contains only the elements that are checked. Like the first approach, associate this new collection to the relationship's ArrayCollection and call the flush method on the entitymanager.