JPA update doesn't work in a many-to-many relationship

问题

I have 3 tables:

• customer(idCustomer,...)
• is_managed(idCustomer,idPerson)
• sales_person(idPerson,...)

There is a @ManyToMany relation between customer and sales_person.

When I perform a delete, then it works fine: the customer, is_managed and sales_person are deleted.

But when I perform an update, then the customer and is_managed are updated, but the sales_person not.

For example, if I update a customer by deleting the sales_person, it's deleted in is_managed table, but not in sales_person table.

How is this caused and how can I solve it?

Here's the relevant code:

// update customer
public String updateCustomer(Customer customer,ArrayList<Sales_person> sales_persons,ArrayList<Involved_group_relation> involved_groups, Macro_market macro_market)throws IOException {

   // insert the sales_person attached to the customer
   ArrayList<Sales_person> sales_personC = new ArrayList<Sales_person>();
   sales_personC.addAll(sales_persons);

    customer.setSalesPersons_BelongTo(sales_personC); // insert in customer the sales_persons

    em.merge(customer);
    return customer.getNameCustomer();
}

// entity customer
@Entity
@Table(name="customer")
public class Customer implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue( strategy = GenerationType.IDENTITY)
    private Long idCustomer;

    private String titleTypeAccount;
    private String nameCustomer;

    /** RELATIONS **/
    // CUSTOMER - SALES_PERSON
    @ManyToMany(
            cascade={CascadeType.ALL}
    )
    @JoinTable(
        name="is_managed",
        joinColumns=@JoinColumn(name="idCustomer"),
        inverseJoinColumns=@JoinColumn(name="idPerson")
    )
    private Collection<Sales_person> salesPersons_BelongTo;
        ...
        ...

// entity sales_person
@Entity
@Table(name="sales_person")
public class Sales_person implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    private Long idPerson;

    private String nameSalesPerson;
    private String jobFunction;
    private String titleOrganization;

    @ManyToMany(
        mappedBy="salesPersons_BelongTo"
    )
    private Collection<Customer> customers;
    ...
    ...

回答1:

If you want the SalesPerson to be deleted from the database, then you must call em.remove() on the SalesPerson. Calling merge() is not enough.

Also, if you want the SalesPerson's changes to be merged, you must call merge() on the SalesPerson as well, or set cascade merge on the salesPersons_BelongTo relationship.

Also ensure you are maintaining both sides of the bi-directional relationship, not just one side.

来源：https://stackoverflow.com/questions/15835741/jpa-update-doesnt-work-in-a-many-to-many-relationship