CODEWITHSUNDEEP
hibernatejpa
greyfox
greyfox

Reputation: 6606

JPA Persist Relationships

If I have the following Entity object which has several foreign key relationships how do I handle form submission when I don't get the relationship object back in the request.

The entity might look something like this:

@Entity
@Table(name = "employee")
public class Employee implements Serializable {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "id")
private Long id;

@Column(name = "first_name")
private String firstName;

@Column(name = "last_name")
private String lastName;

@Column(name = "middle_name")
private String middleName;

@Column(name = "login_id")
private String loginId;

@ManyToOne(fetch = FetchType.EAGER, optional = false)
@JoinColumn(name = "department_id")
private Department department;

@ManyToOne(fetch = FetchType.EAGER, optional = false)
@JoinColumn(name = "employment_type_id")
private EmploymentType employmentType;

@ManyToOne(fetch = FetchType.EAGER, optional = false)
@JoinColumn(name = "citizenship_id")
private Citizenship citizenship;

public Employee() {
}
}

But this is the HTTP POST request I'll be receiving.

id: 1
firstName: Bob
lastName: Dole
middleName: Trump
loginId: bdole
departmentId: 1
employmentTypeId: 2
citizenship_id: 4

JPA wants to save the relationship object, not the ID. However doing all those look ups also seems inefficient, turning the IDs into the required objects to persist. Is there a better way to handle this?

Upvotes: 0

Views: 41

Answers (1)

Tanvi B
Tanvi B

Reputation: 1567

Use getReference http://docs.oracle.com/javaee/6/api/javax/persistence/EntityManager.html#getReference%28java.lang.Class,%20java.lang.Object%29

It calls the entityManager to load customer object using the id and then set that onto the customer history. In most cases this call would return a proxy with just the id embedded.

Department department = entityManager.getReference(Department.class, departmentId);

Employee employee = new Employee();
employee.setDepartment(department);

Upvotes: 1

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