CODEWITHSUNDEEP
javahibernatemapping
Mateus Viccari
Mateus Viccari

Reputation: 7709

How to specify fixed parameter on hibernate join mapping?

I have the following case, where I have two classes/tables:

public class Parent {
    @Id
    @Column(name="parent_id")
    private Integer parentId;

    @ManyToOne
    @JoinColumn(name="child_id") //Notice here that i only specified one of the two id columns of the Child class
    private Child child;
    ...
}

public class Child {
    @Id
    @Column(name="child_id")
    private Integer childId;

    @Id
    @Column(name="alive")
    private Boolean alive;

    @Column(name="name")
    private String name;
}

As you can see, child has two primary keys, which means i can have the same child_id in two rows, one with alive=true and another with alive=false, but i don't have the alive attribute on the parent:

PARENT TABLE
parent_id | child_id
--------------------
500       | 1

CHILD TABLE
child_id | alive | name
--------------------------
1        | TRUE  | DONALD
1        | FALSE | HILLARY

I want hibernate to generate the join clause inserting the alive attribute, only when alive=true, for example:

select * from Parent inner join Child on Child.child_id=Parent.child_id and Child.alive=true

Is there a way to do this, so when i execute a query like select p from Parent p it executes the query as expected?

Upvotes: 0

Views: 990

Answers (1)

StanislavL
StanislavL

Reputation: 57421

For the Parent class you can use 

@JoinColumnOrFormula(formula=@JoinFormula(value="(SELECT a.id 
                                                  FROM Child c 
                                                  WHERE c.child_id=child_id 
                                                  and alive=true)", 
   referencedColumnName="child_id")

Posted correct comment as an answer

Upvotes: 1

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