Cascading problems

Question

Hi,
We are testing some JPA code and are having problems with the cascading behaviour of our test code.
Firstly, we have a main Person bean with the following attributes and is the owning side of the two relationships:
@Id
@Column(name = "id")
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;
@Column(name = "firstname")
private String firstname;
@Column(name = "lastname")
private String lastname;
@ManyToOne(fetch = FetchType.EAGER, cascade = CascadeType.ALL, targetEntity = OccupationJpaImpl.class)
@JoinColumn(name = "occupation_id")
private Occupation occupation;
@ManyToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL, targetEntity = BeverageJpaImpl.class)
@JoinTable(name = "person_beverage", joinColumns = { @JoinColumn(name = "person_id") }, inverseJoinColumns = { @JoinColumn(name = "beverage_id") })
private Set<Beverage> beverages;Each of the non-owning sides are set up as follows:
Beverage:
@Id
@Column(name = "id")
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;
@Column(name = "description")
private String description;
@Column(name = "alcoholic")
private Boolean alcoholic;
@ManyToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL, mappedBy = "beverages", targetEntity = PersonJpaImpl.class)
private Set<Person> people;
Occupation:
@Id
@Column(name = "id")
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;
@Column(name = "description")
private String description;
@OneToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL, mappedBy = "occupation", targetEntity = PersonJpaImpl.class)
private Set<Person> people;We have a few tests of which one works and the rest fail:
1 - If we remove a Beverage from a collection of beverages belonging to a Person and merge the Person then the underlying join table has the appropriate mapping record removed which we want.
2 - If we remove a Person from a collection of people belonging to a Beverage and merge the Beverage then the underlying join table does not have the appropriate mapping record removed.
3 - If we delete an Occupation then the associated people, and any of their associated records, are not deleted but rather an attempt is made to insert a null into the occupation_id column of the underlying person table. This does not happen if there is no many-to-many relationship on Person to Beverage, then the people are deleted.
Any explanation as to why 2 and 3 do not work as expected would be greatly appreciated.
Regards,
Chris.

Answer 1

I am no JPA expert but I did have a similar problem recently. My problem was having the cascade setting in both the owning and non-owning entity classes. When I merged a non-owning entity it would cascade it's current data up into the owning entity which in my case would overwrite data I had just set and merged in the owning entity.
I believe you need to remove the cascade setting in your non-owning entity classes and / or know exactly what is set in each property of your non-owning entities before you attempt to merge them so you will know what table modifications you can expect to see.
In my particular case cascading in both directions was causing my problems.
Hope this helps.