如何在外键与联接表和单向休眠状态下进行一对一关联

Question

I wish to have a one to one association with a join table in unidirectional way. -

Tables :

1. A (A_id, D_id, A_Data)
2. B (A_id, C_id) // Join table just contain relation between A and C

3. C (C_id, C_Data)

    Class A { . . @OneToOne(cascade = CascadeType.ALL) @JoinTable(name = "B", joinColumns = @JoinColumn(name = "A_id", referencedColumnName = "A_id"), inverseJoinColumns = @JoinColumn(name = "C_id", referencedColumnName = "C_id")) private C c; } 

I am using hibernate with jpa 2.0. Entity D is not important in the model hence ignored. I only wish to read data ,hence insert/update/delete use cases should not be concern, but one can suggest best practice in that case also.

This setup does not work. Can some one suggest how to do it in correct way?

It gives following exception

org.hibernate.MappingException: Unable to find column with logical name: A_id in org.hibernate.mapping.Table(A) and its related supertables and secondary tables

Answer 1

In order to get your desired schema:

    // Given the following C entity
    @Entity
    public class C {

        @Id
        @Column(name = "C_ID")
        private long id;

        private String C_Data;

        //...
    }


    // A Entity should be 
    @Entity
    public class A {

        @Id
        @Column(name = "A_ID")
        private long id;

        private String A_Data;

        @OneToOne(cascade = CascadeType.ALL )
        @JoinTable(name = "B", joinColumns = @JoinColumn(name = "A_id"), inverseJoinColumns = @JoinColumn(name = "C_id", unique = true))
        private C c;

        //...

    }

I've omitted referencedColumnName , so hibernate will map it to the entity primary key.

Note also that A_id column of B table will be the primary key.