Question

I have a pretty simple JPA @ManyToMany relationship set up in my application. A Product is a part of one or more OrderSystems. Each OrderSystem can have many Products. It’s a typical many-to-many relationship.

The problem I’m fighting with is this: If I use orderSystems.remove() to remove a reference from a Product to an OrderSystem, the entry appears to be removed (within that session). However, the entry isn’t removed from the cross-reference table on flush, and when I reload the Product it has the previous set of OrderSystems.

I have the following code:

@Entity @Table(name = 'p_product_versions') @Validation public class Product {     private List<OrderSystem> orderSystems;     @ManyToMany     @JoinTable(name = 'p_order_systems_has_product_versions',              joinColumns =                 @JoinColumn(name = 'p_product_versions_prod_version_id'),             inverseJoinColumns =                 @JoinColumn(name = 'p_order_systems_system_id'))     public List<OrderSystem> getOrderSystems() {         return orderSystems;     }  }  @Entity @Table(name = 'p_order_systems') @Validation public class OrderSystem {     private List<Product> products;     @ManyToMany (mappedBy = 'orderSystems')     public List<Product> getProducts() {         return products;     } } 

Can anyone point me at what I’m missing here?

Answer 1

Turned out that the problem was that I was not clearing the relationship in both directions. I would remove a Product from the OrderSystem but not remove the OrderSystem from the Product.