JPA - Secondary Table mapping direction

Question

I've got two tables:

CREATE TABLE Checkin (
  ID int primary key,
  foo varchar(100),
  bar varchar(100),
  FK_type int foreign key references Type(ID)
)

CREATE TABLE Type (
  ID int primary key,
  type varchar(100)
)

Since the secondary table only stores labels, I'd like to map the values directly into my entity. I figured it should be possible using @SecondaryTable...

@Table(name = "Checkin")
@SecondaryTable(name = "Type",
    pkJoinColumns = @PrimaryKeyJoinColumn(name="FK_type", referencedColumnName = "ID")
)
class Checkin {
  @Id
  private Integer id;

  private String foo;
  private String bar;

  @Column(name="FK_type", table="Type")
  private String type;
}

Unforunately, it would seem that the @SecondaryTable annotation works the other way around, meaning it wants my actual primary data table with the most columns to be the one joining. So I get thrown the error

Invalid column name 'FK_type'.

Is there a way to solve that through different annotations or do I really need to build the whole construct the other way round and have the main entity refer to "Type" and "Chekin" be the secondary table?

Answer 1

You should join Type entity in Checkin:

class Checkin {
      @Id
      private Integer id;
    
      private String foo;
      private String bar;
    
      @OneToOne(cascade = CascadeType.ALL)
      @JoinColumn(name = "type_id", referencedColumnName = "id")
      private Type type;
    }

Answer 2

Try to correct this:

@Column(name="FK_type", table="Type")
private String type;

to this:

@Column(name="type", table="Type")
private String type;

The table Type just do not have the FK_type column, as I understand you want to use Type.type here.

PS You can omit to use referencedColumnName if this is a reference to the PK.