cannot insert null in one to many relationship hibernate annotation

Question

I have a class A{Set b .....} which holds references of class B as Set. It is one to many relationship. Both class have sequencer in oracle. I put cascade to all in hibernat

Answer 1

I ran into the same problem and solved it by using the mappedBy attribute of the @OneToMany annotation in Class A:

@OneToMany(cascade = CascadeType.ALL, mappedBy = "m_a")
private Set b;

Here, m_a is the field in Class B that refers to Class A:

@JoinColumn(name = "aId", nullable = false)
@ManyToOne
private A m_a;

This way, the @JoinColumn is only specified in one place, no duplicated code.