Im trying to get a list with results from join with two tables, but always get error. What i want is List with person and job name Error Cannot invoke "org.hibernate.hql.internal.ast.tree.FromElement.setAllPropertyFetch(boolean)" because "fromElement" is null My tables Person int id text name int job_id (foreign key with table JOB(id)) Job int id text name Entities DAO Answer To be able

Hibernate Join between 2 tables with foreign key

Im trying to get a list with results from join with two tables, but always get error. What i want is List with person and job name

Error
- Cannot invoke “org.hibernate.hql.internal.ast.tree.FromElement.setAllPropertyFetch(boolean)” because “fromElement” is null
My tables
- Person
  - int id
  - text name
  - int job_id (foreign key with table JOB(id))
- Job
  - int id
  - text name

Entities

@Entity
@Table(name = "person")
public class Person{

@Id
@Column(name = "id")
int id;
@Column(name = "name")
String name;
@Column(name = "job_id")
int jobId;

public int getId() {
    return id;
}

public void setId(int id) {
    this.id = id;
}

public int getJobId() {
    return jobId;
}

public void setJobId(int jobd) {
    this.jobId= jobId;
}
public String getName() {
    return name;
}

public void setName(int name) {
    this.name= name;
}


@Entity
@Table(name = "job")
public class Job{

@Id
@Column(name = "id")
int id;
@Column(name = "name")
String name;

public int getId() {
    return id;
}

public void setId(int id) {
    this.id = id;
}

public String getName() {
    return name;
}

public void setName(int name) {
    this.name= name;
}

    public class PersonDAO {
    @Autowired
    private SessionFactory sessionFactory;

    public void setSessionFactory(SessionFactory sf) {
        this.sessionFactory = sf;
    }

    public List<Person> getAllPerson() {
        Session session = this.sessionFactory.getCurrentSession();
        List<PersonResponse> list = session.createQuery("from Person p left join p.jobId").list();
    }
}

- PersonResponse
    - POJO with Person parameteres/variables without annotations and job name.

Answer

To be able to use left join in hql you should correct your mapping for Person in the following way:

@Entity
@Table(name = "person")
public class Person
{
   @ManyToOne
   @JoinColumn(name = "job_id")
   Job job;

   // ...
}

and then you will be able to write hql query like this:

List<Person> list = session.createQuery("select p from Person p left join p.job").list();

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Answer