How persist new created parent and child entities with hibernate?

Question

Here is entities:

@Entity
public class Parent {
    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    private Long id;
    @OneToMany(fetch = FetchType.EAGER, mappedBy = "parent" ,cascade = CascadeType.ALL)
    @Fetch(value = FetchMode.SUBSELECT)
    private Collection<Child> children;
}

@Entity
public class Child {
    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    private Long id;

    @ManyToOne(cascade = CascadeType.ALL)
    private Parent parent;

}

For managing this entities I use spring data (rest). I need to save entities like that:

Parent parent = new Parent();
Child child = new Child()
parent.setChildren(Arrays.asList(child))
springDataRepository.save(parent);

And only Parent object is persisted.

Also as I spot parent and child are created without id . So should I persist only parent , then set it to child and persist child ? Can these operation be done with one parent saving action?

Answer 1

See this reply: https://stackoverflow.com/a/7428143

Instead of:

parent.setChildren(Arrays.asList(child))

you should use:

parent.setChildren(new ArrayList<>(Arrays.asList(child)))