javahibernatejpaannotationshibernate-annotations

JPA Annotations - How to retrieve a single value from a different table than the current object?


How do you map a single value from a column in another table to the current object?

Example:

class Foo {
    @Id
    @Column(name="FOO_ID")
    private String fooId;

    @Column(name="FOO_A")
    private String fooA;

    //Column to map to another table?
    //is a one to one mapping - but don't want a separate object for this.
    private String barCode;
}

Table: Fields

Foo: FOO_ID, FOO_A

Bar: FOO_ID, BAR_CODE

How do I retrieve the BAR_CODE field without creating a separate object (or a secondary table) using JPA annotations?


Solution

  • Use a secondary table. This allows you to map for an entity, on a one-to-one basis, another table and define column mappings that use it.

    Example:

    @Entity
    @Table(name = "foo")
    @SecondaryTable(name = "other_table", pkJoinColumns=@PrimaryKeyJoinColumn(name="id", referencedColumnName="FOO_ID"))
    public class Foo {
        @Id
        @Column(name="FOO_ID")
        private String fooId;
    
        @Column(name="FOO_A")
        private String fooA;
    
        @Column(table="OtherTable", name="barCode")
        private String barCode;
    }