JPA Hibernate two foreign keys to the same table

问题

I've found two topics this and this, but still cannot populate it to my case. I have an Account. I can do Payments from one account to another. For that purpose I want to store payer_account_id and receiver_account_id in Payments table. How can I map that using Annotations?

@Entity
public class Account {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private Double balance;

    //mapping here to Payments Entity
    private ???

}


@Entity
    public class Payments {
        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
         private Long id;
        private Double ammount;

        //mapping here to Account Entity
        private Account payerAccount;

        //mapping here to Account Entity
        private Account receiverAccount;

    }

回答1:

It seems to be an one-to-many relations. If you want to do a bidirectional relations use these annotations.

@Entity
public class Account {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private Double balance;

    @OneToMany(mappedBy="payerAccount", fetch = FetchType.EAGER)
    private Collection<Payments> payers;

    @OneToMany(mappedBy="receiverAccount", fetch = FetchType.EAGER)
    private Collection<Payments> receivers;


    /* GETTERS AND SETTERS */
}

@Entity
public class Payments {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private Double ammount;

    @ManyToOne
    @JoinColumn(name="payer_account_id")
    private Account payerAccount;

    @ManyToOne
    @JoinColumn(name="recever_account_id")
    private Account receiverAccount;

    /* GETTERS AND SETTERS */

}

In this code i use EAGER fetch, it means that your lists will be automatically populated if you have an object account.

Hope it helps.

回答2:

How about this:

    //mapping here to Account Entity
    @ManyToOne  
    private Account payerAccount;


    //mapping here to Account Entity
    @ManyToOne
    private Account receiverAccount;

来源：https://stackoverflow.com/questions/32698294/jpa-hibernate-two-foreign-keys-to-the-same-table

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