ORM: EclipseLink AssociationOverride "Persistent type of override attribute cannot be resolved" - orm

Question

I am building an application that has a database of students, courses, and it also keeps track of all the courses that each student is taking,
I have an entity for Course and Student, and they have a one to many relationship with entity StudentCourses and an embeddable class of StudentCoursesID.
In the StudentCourse when I try to use the annotation AssociationOverride it gives me a problem saying
"Persistent type of override attribute "student" cannot be resolved"
"Persistent type of override attribute "course" cannot be resolved"
and
"Embedded ID class should not contain relationship mappings"
I dont understand if i did the mapping wrong or if there is a disconnection between my entities and classes.
Below I have each of the the entity starting with StudentCourses which is giving me issues.
StudentCourses
package jpa.entitymodels;
import javax.persistence.*;
#Entity
#Table(name = "student_courses")
#AssociationOverrides({
#AssociationOverride(name = "student", joinColumns = #JoinColumn(name = "sEmail")),
#AssociationOverride(name = "course", joinColumns = #JoinColumn(name = "cId"))
})
public class StudentCourses {
private StudentCoursesId id = new StudentCoursesId();
public StudentCourses() {
}
public StudentCourses(StudentCoursesId id) {
this.id = id;
}
#EmbeddedId
public StudentCoursesId getId() {
return id;
}
StudentCoursesId
package jpa.entitymodels;
import javax.persistence.Embeddable;
import javax.persistence.ManyToOne;
import java.io.Serializable;
#Embeddable
public class StudentCoursesId implements Serializable {
private static final long serialVersionUID = 1L;
private Student student;
private Course course;
public StudentCoursesId() {
}
#ManyToOne
public Student getStudent() {
return student;
}
public void setStudent(Student student) {
this.student = student;
}
#ManyToOne
public Course getCourse() {
return course;
}
Course
package jpa.entitymodels;
import javax.persistence.*;
import java.util.ArrayList;
import java.util.List;
#Entity
#Table(name = "course")
public class Course {
#Id
#Column(name = "id")
int cId;
#Column(name = "name")
String cName;
#Column(name = "instructor")
String cInstructorName;
#OneToMany(mappedBy = "id.course", fetch = FetchType.LAZY)
List<StudentCourses> studentCourses = new ArrayList<>();
Student
package jpa.entitymodels;
import java.util.ArrayList;
import java.util.List;
import javax.persistence.*;
#Entity
#Table(name="student")
public class Student {
#Id
#Column(name = "email")
String sEmail;
#Column(name = "name")
String sName;
#Column(name = "password")
String sPass;
#OneToMany(mappedBy = "id.student", fetch = FetchType.LAZY, cascade = CascadeType.ALL)
List<StudentCourses> studentCourses = new ArrayList<>();

Answer 1

The 'student' doesn't exist in StudentCourses which is why you get the error. Overrides you want to apply to the embeddable need to be defined on the embeddable mapping, not the StudentCourses class.
#Entity
#Table(name = "student_courses")
public class StudentCourses {
#Embedded
#AttributesOverride({
#AttributeOverride(name = "student", joinColumns = #JoinColumn(name = "sEmail")),
#AttributeOverride(nname = "course", joinColumns = #JoinColumn(name = "cId"))})
private EmbeddableClass embeddableClass;
public StudentCourses() {
}
}
JPA requires an ID class that has the simple pk types within it (or other nested composite PK classes, not relationships), requiring StudentCoursesId have a int/string property for the cId and sEmail. If you want to have mappings to course/student, maybe see the mapsId annotation or alternatively, I would map it like this:
#Entity
#Table(name = "student_courses")
#IdClass(StudentCoursesId.class)
public class StudentCourses {
#Id
#JoinColumn(name = "sEmail")
Student student;
#Id
#JoinColumn(name = "cId")
Course course;
}
public class StudentCoursesId implements Serializable {
private static final long serialVersionUID = 1L;
private String student;//Name matches id property in StudentCourses
private int course;
}