如何在Databse中使用2个主键映射JPA实体

Question

In my database model I have 2 primary keys. I am using JPA with hibernate.

My database model is like

---

USR_INFO_TBL

COMPANY_ID
PERSONAL_ID
FIRST_NAME
LAST_NAME
EMAIL
USR_INFO_TBL_PK

---

Now my JPA entity is like below

 @Entity 
 @Table("USR_INFO_TBL")
 public class UerInfo{
@ID(name ="COMPANY_ID")
private String companyID;

private String personalID;   //what should i write here
@COLUMN(name="firstName") 
private String firstName;

@COLUMN(name="lastName ")
private String lastName;

@COLUMN(name="email")
private String email;

//setters and getters
}

How the 2 primary keys can be mapped to a JPA Entity Can you plz modify the above code.I gone through some posts as i was new to JPA AND HIBERNATE concepts.I was in a confusion

Thanks

Answer 1

You should create a class annotated with @Embeddable containing the components of the composite key, and in your current, User entity you should create a field with this new type.

@Entity 
@Table("INFO_USR_TBL")
public class User {
    @EmbeddedId
    private UserId id;

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

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

    @Column(name="email")
    private String email;

    //setters and getters
}

@Embeddable
public class UserId {
    @Column(name="COMPANY_ID")
    String companyId;
    @Column(name="PERSONAL_ID")
    String personalId;
}

Answer 2

In the JPA specification, it states "A composite primary key must either be represented and mapped as an embeddable class or must be represented as an id class and mapped to multiple fields or properties of the entity class".

You may change your code to below:

public class UserId {
    String companyId;
    String personalId;
}

@Entity 
@Table(name="INFO_USR_TBL")
@IdClass(UserId.class)
public class User {

    @Id
    @Column(name ="COMPANY_ID")
    private String companyID;
    @Id
    @Column(name ="PERSION_ID")
    private String personalID;

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

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

    @Column(name="EMAIL")
    private String email;

    //setters and getters
}

Answer 3

Please, check this article JPA primary keys , especially "Composite Primary Key" and "Embedded Primary Key" paragraphs. I think, your case is "Embedded Primary Key" when you need to define class, that will contain all primary key parts you actually need to have.