QueryDSL Left Join not mapping properly with JPA entity

Question

QueryDSL is not working properly with JPA for left join. I am using queryDSL version 4.2.1 and mapping the response directly to javax.persistence entity. For Left join/Right join, the joining condition it's not working. It fetches every entity disregarding the joining condition(here it's name = "testName") when entity1.getEntity2() is being called.

Is there any other way applicable for this case to map the result after JOIN tables ?

JPAQuery<Entity1> query = new JPAQuery<>(entityManager);
query.from(table1);
query.leftJoin(table2).on(table2.id.eq(table1.id).and(table2.name.eq("testName"));
List<Entity1> list = query.fetch();

@Entity
public class Entity1{

 private Integer id;

 @OneToMany(mappedBy = "entity1", fetch = FetchType.LAZY)
 private List<Entity2> entity2;
}

Simon Martinelli Simon Martinelli · Accepted Answer · 2019-05-23T10:54:06

An left or right join is an outer join.

So if you use left join all records from the left (in your case table1) will be selected.

If you only want records from table1 if there are corresponding records on table2 you have to use innerJoin.

JPAQuery<Entity1> query = new JPAQuery<>(entityManager);
query.from(table1);
query.innerJoin(table2).on(table2.id.eq(table1.id).and(table2.name.eq("testName"));
List<Entity1> list = query.fetch();

QueryDSL Left Join not mapping properly with JPA entity

1 Answers