CODEWITHSUNDEEP
javaspringhibernate
Ramanujan R
Ramanujan R

Reputation: 1719

Child object properties are NULL, after parent update in hibernate

Have following hibernate POJOs

@Entity
Class Parent {
  long id // id, generate auto increment
  Child child // many to one, eager fetch, no cascade
}

@Entity
Class Child{
  long id // id, generate auto increment
  String name;
}

Have following spring service

@Transactional
void myMethod() {
 Parent parent = session.getParent(id); // id=10
 // Here parent has child object {id: 20, name: "FirstChild"}

 Child newChild = new Child(21); //DB has a child row with id 21 and name "SecondChild"
 parent.setChild (newChild);

 session.update(parent);

 System.out.println(parent.getChild.getName())
 // This print NULL
}

I expected this will print "SecondChild", as parent is a persistent object and we are in same hibernate session. Where I'm wrong ?

Upvotes: 1

Views: 525

Answers (1)

StanislavL
StanislavL

Reputation: 57381

 Parent parent = session.getParent(id); // id=10
 // Here parent has child object {id: 20, name: "FirstChild"}

 Child newChild = session.getChild(21); 
 parent.setChild(newChild);

 session.update(parent);

Retrieve the child from DB rather than creating it manually.

Upvotes: 2

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