How to remove the compound PK from a Symfony2 ManyToMany

Question

I need to allow multiple Products to be present in a Cart. I do not want to increase a quantity column, I actually want the same Product entity in the Cart twice. I want to reuse the Product entities and not create a CartProduct intermediary too.

Cart ManyToMany Product

However, the table is created by doctrine:schema:update with a compound primary key of cart_id + product_id. This prevents me adding the same Product twice.

How do I solve this?

This is not the only use-case I have where I need a ManyToMany to support duplicate entries. Is this just not possible with Symfony2/Doctrine?

Answer 1

It's not so much a limitation of doctrine as it is of relational databases. Every row needs to have a unique primary key which, by default in Doctrine 2, would be product_id,cart_id.

The only way around it is to make yourself an explicit CartProduct entity and add at least one more column. Not that hard to do. Just establish OneToMany relations to it from Cart and Product.