Emulating a LEFT JOIN in Spring Entity - spring

Question

In effect, what I am trying to do is this...
SELECT a.*, b.description, c.description FROM a
LEFT JOIN b ON b.code = a.b_code
LEFT JOIN c ON c.code = a.c_code
I would like to map this entirely using Spring/JPA framework. I've played around with #SecondaryTable only to find out that it will not work in thie case, and I've been getting a number of errors while trying to map it using #OneToOne or #JoinColumn. Here are my current entity classes...
#Entity
#Table(name = "a")
public class a {
#Id
#Column(name = "id")
private String id;
#Column(name = "b_code")
private String bCode;
//I'd like to have b.description here
#Column(name = "c_code")
private String cCode;
//I'd like to have c.description here
}
#Entity
#Table(name = "b")
public class b {
#Column(name = "code")
private String code;
#Column(name = "description")
private String description;
}
#Entity
#Table(name = "c")
public class c {
#Column(name = "code")
private String code;
#Column(name = "description")
private String description;
}

Answer 1

You need to use #JoinColumn with referencedColumnName as shown below.
#Entity
#Table(name = "a")
public class a {
#Id
#Column(name = "id")
private String id;
#Column(name = "b_code")
private String bCode;
//I'd like to have b.description here
#Column(name = "c_code")
private String cCode;
//I'd like to have c.description here
#OneToOne // this should be based on your joining
#JoinColumn(name = "b_code", referencedColumnName = "code", insertable = false, updatable = false)
B b;
#OneToOne// this should be based on your joining
#JoinColumn(name = "c_code", referencedColumnName = "code", insertable = false, updatable = false)
C c;
}
#Entity
#Table(name = "b")
public class B {
#Column(name = "code")
private String code;
#Column(name = "description")
private String description;
}
#Entity
#Table(name = "c")
public class C {
#Column(name = "code")
private String code;
#Column(name = "description")
private String description;
}