hibernate parent child relationship

Question

Let's say I have entity A and entity B. Entity A have @OneTomany relationship with B.

I want to persist row in A only if it has one or more child object's associated with it else throw an exception.

How can i achieve the above requirement in hibernate

Answer 1

You neglected to mention what version of Hibernate you are using. In any case, this falls within the purview of validation. Luckily, in both Hibernate 3 and 4 you can utilize Hibernate Validator to do the job:

public class EntityB implements Serializable {
}

public class EntityA implements Serializable {
    @NotNull
    @Size(min = 1)
    private Set<EntityB> relatedEntities;
}

You may need to pull in the Hibernate Validator jars into your project in order to be able to do this.

Answer 2

Entity class:Register.class

public class Register{

private Long regId;

@OneToMany(mappedBy = "reg")

private Set addrSet;

public Set getAddrSet() {

    return addrSet;

}

public void setAddrSet(Set<Address> addrSet) {
    this.addrSet = addrSet;
}

}

Entity Class:Address.java

public class Address{

object values;

@ManyToOne

private Register reg;

public Register getReg() {

    return reg;

}

public void setReg(Register reg) {
    this.reg = reg;
}

}

public void class searchObject(){

public List lst; public register searchRegisterRow(Long regId){

  Session session = null;

 SessionFactory sessionFactory = null;

 register result = null; 

    try{    

       sessionFactory = new Configuration().configure().buildSessionFactory();      
        session =sessionFactory.openSession();
       String SQL_QUERY ="from Register r where r.redId = "+regId;
       Register reg = session.createQuery(SQL_QUERY);  

             for(Iterator it=lst.iterator();it.hasNext();){


                             reg=(Register)it.next();

            if(reg.getAddrSet().size() > 0){

                              result = reg;

                            }
                            else{

                                throw new Exception();

                            }

        }

        return result;
    }
    }catch(Exception e){

        System.out.println(e.getMessage());

    }finally{
        // Actual contact insertion will happen at this step
        session.flush();

        session.close();

        }

} }

I think you should try above code. this will help you.