Using nested property access in a JPA repository for composite key entity implemented using #EmbeddedID approach returning null values - spring

Question

My SQL view :-
CREATE OR REPLACE VIEW my_view
AS
SELECT
col1,
col2,
col3,
col4,
col5,
col6
FROM
my_table
My JPA entity :-
#Entity
#Table(name = "my_view")
#Getter
#Setter
public class MyEntity {
#EmbeddedId
private MyPk myPk;
#ManyToOne(fetch = FetchType.LAZY, optional = false)
#JoinColumn(name = "col1", insertable = false, updatable = false)
private Entity1 entity1 ;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "col2", insertable = false, updatable = false)
private Entity2 entity2;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "col3", insertable = false, updatable = false)
private Entity3 entity3;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "col4", insertable = false, updatable = false)
private Entity4 entity4;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "col5", insertable = false, updatable = false)
private Entity5 entity5;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "col6", insertable = false, updatable = false)
private Entity6 entity6;
}
My Embedded Id class:-
#NoArgsConstructor
#EqualsAndHashCode
#AllArgsConstructor
#Embeddable
public class MyPk implements Serializable {
#ManyToOne(fetch = FetchType.LAZY, optional = false)
#JoinColumn(name = "col1", insertable = false, updatable = false)
private Entity1 entity1 ;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "col2", insertable = false, updatable = false)
private Entity2 entity2;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "col3", insertable = false, updatable = false)
private Entity3 entity3;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "col4", insertable = false, updatable = false)
private Entity4 entity4;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "col5", insertable = false, updatable = false)
private Entity5 entity5;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "col6", insertable = false, updatable = false)
private Entity6 entity6;
}
My JPA Repository :-
public interface MyEntityRepository extends JpaRepository<MyEntity, MyPk> {
List<MyEntity> findByMyPk_Entity1_Id(Long id);
}
Entity1 has an attribute id
I have tried #IdClass approach for composite key and many other solutions related to composite key but all are giving me some kind of error during runtime
This above approach is giving me no runtime error but giving null elements when invoking findByMyPk_Entity1_Id method but its giving correct count of elements in list
I cant use any kind of sequence from table or any other unique column approach dur to my underlying code. Also I tried using #mapIds approach but its also giving null elements.
For some reason JPA repository is not able to convert into entities but its able to give correct count of entities fetched
Also when using findAll method of repository in debugger its giving me proper entities list with no null elements but when searching through nested property i am not able to get entities
spring-data-jpa:1.9.4 version
hibernate-jpa-2.1-api:1.0.0
java 8
< Its a legacy project :") >

Answer 1

I don't know what you really have mapped in your table/view that you really need all 6 columns to uniquely identify a row. Assuming you do, and assuming they are all references to other tables that you want to have mapped in your entity, there are a number of approaches. The easiest, IMO more flexible approach might be this:
#Entity
#Table(name = "my_view")
public class MyEntity {
#EmbeddedId
private MyPk myPk;
#ManyToOne(fetch = FetchType.LAZY, optional = false)
#JoinColumn(name = "col1")
#MapsId("entity1")
private Entity1 entity1 ;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "col2")
#MapsId("entity1")
private Entity2 entity2;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "col3")
#MapsId("entity1")
private Entity3 entity3;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "col4")
#MapsId("entity1")
private Entity4 entity4;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "col5")
#MapsId("entity1")
private Entity5 entity5;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "col6")
#MapsId("entity1")
private Entity6 entity6;
}
#Embeddable
public class MyPk implements Serializable {
private Integer entity1 ;//use the ID type from Entity1's primary key
private Integer entity2;
private Integer entity3;
private Integer entity4;
private Integer entity5;
private Integer entity6;
}
Mappings in the MyPk embeddable class will be basic mappings, and pick up the column name settings from the entity ManyToOne mappings. Should you try to ever write one out (you can't write to views, but JPA treats everything as a table), you only need to set the appropriate relationships and JPA will extract the fk values to populate your MyEntity.myKey.entityX values for you.
Having both the embedded and the ManyToOne references means you can have the fk values within your entity and accessible without having to fetch the related entity just for the ID value.