JPA 2 个不同的本地查询，具有相同的 class 作为实体

Question

I am new to JPA. Currently I am writing a native query with @Query annotation. I have a class similar to the below

@Column(name="field1")
Private String field1;

@Column(name="field2")
Private String field2;

@Column(name="field3")
Private String field3;

I am writing 2 queries where 1 query has field 2 included in select projection and other does not include field 2. How can I use same class for both of the queries? I tried @Transient annotation. But it made values of both queries as null.

Answer 1

You have lot of options to do that.

Option 1: Projections from Spring Data JPA without @Query

interface MyProjection{
    String getField1();
    String getField3();
}
public interface MyRepository extends JpaRepository<Entity, Integer> {

    List<MyProjection> findAll();
}

Option 2: Projections from Spring Data JPA with @Query (quite similar to Option 1)

interface MyProjection{
    String getField1();
    String getField3();
}
public interface MyRepository extends JpaRepository<Entity, Integer> {
    @Query("SELECT p FROM Entity p")
    List<MyProjection> customFindEntity();
}

Option 3: Projections from Spring Data JPA with @Query without any interface

public interface MyRepository extends JpaRepository<Entity, Integer> {
    @Query("SELECT p.field1,  p.field2 FROM Entity p")
    List<Object> customFindEntity();
}

Option 4: Projections from Spring Data JPA with @Query an native query (quite similar to Option 2)

interface MyProjection{
    String getField1();
    String getField3();
}
public interface MyRepository extends JpaRepository<Entity, Integer> {
    @Query("SELECT field1, field3 FROM Entity p", nativeQuery = true)
    List<MyProjection> customFindEntity();
}

Option 5: Use Native query and return list of object array

You have to extract your data from the list of array.

public interface MyRepository extends JpaRepository<Entity, Integer> {
    @Query("SELECT field1, field3 FROM Entity p", nativeQuery = true)
    List<Object[]> customFindEntity();
}