'univ_orientation.dz.Entity.cursusGlobale.Student_idStudent'上的@OneToOne或@ManyToOne引用了一个未知实体：int

Question

I'm working in a web app with Hibernate 5 and SpringMVC, when I worked just with simple tables (without relationships between any tables) everything work okay, update, save, delete..., but if I try to add some relationships between tables, and when I mapped, I got this error :

@OneToOne or @ManyToOne on 'univ_orientation.dz.Entity.cursusGlobale.Student_idStudent' references an unknown entity: int

I had searched to solve this issue, I found out that its a configuration problem, Hibernate doesn't recognize class cursusGlobale as an entity.

My question is why Hibernate doesn't recognize class cursusGlobale as an entity when I work with relationships, but it does if I work just with simple tables without relationships between tables?

  package univ_orientation.dz.Entity;

 import javax.persistence.CascadeType;
 import javax.persistence.Column;
 import javax.persistence.Entity;
 import javax.persistence.GeneratedValue;
 import javax.persistence.GenerationType;
 import javax.persistence.Id;
 import javax.persistence.JoinColumn;
 import javax.persistence.OneToOne;
 import javax.persistence.Table;

@Entity
@Table(name="cursusGlobale")
public class cursusGlobale {

@Id
@GeneratedValue(strategy=GenerationType.IDENTITY) 
@Column(name="idcursusGlobale")
private int idcursusGlobale;

@Column(name="nbrRedoubler")
private int nbrRedoubler;

@Column(name="nbrDette") 
private int nbrDette;


@Column(name="idStudent")
private int idStudent;

@OneToOne( cascade= CascadeType.ALL)
@JoinColumn(name="Student_idStudent")
private int Student_idStudent;



public cursusGlobale() {

}


public cursusGlobale(int nbrRedoubler, int nbrDette, int 
 student_idStudent) {
    super();
    this.nbrRedoubler = nbrRedoubler;
    this.nbrDette = nbrDette;
    idStudent = student_idStudent;
  }



public int getIdcursusGlobale() {
    return idcursusGlobale;
}

public void setIdcursusGlobale(int idcursusGlobale) {
    this.idcursusGlobale = idcursusGlobale;
}

public int getNbrRedoubler() {
    return nbrRedoubler;
}

public void setNbrRedoubler(int nbrRedoubler) {
    this.nbrRedoubler = nbrRedoubler;
}

public int getNbrDette() {
    return nbrDette;
}

public void setNbrDette(int nbrDette) {
    this.nbrDette = nbrDette;
}


public int getIdStudent() {
    return idStudent;
}


public void setIdStudent(int idStudent) {
    this.idStudent = idStudent;
}


}

Answer 1

You have not create a relationship. You are using a java native type int instead of another class Student .

@OneToOne( cascade= CascadeType.ALL)
@JoinColumn(name="Student_idStudent")
private int Student_idStudent;

As the error message clearly says: @OneToOne or @ManyToOne on 'univ_orientation.dz.Entity.cursusGlobale.Student_idStudent' references an unknown entity: int , Student_idStudent is defined as an int, not as an Entity. You will need something more along the lines of

@OneToOne( cascade= CascadeType.ALL)
@JoinColumn(name="Student_idStudent")
private Student student;

Even though it is a class it will be persisted as a Foreign Key to the Student table in the database. This is part of the abstraction provided by JPA.

Reference: JPA Hibernate One-to-One relationship