在Spring Data JPA中按类型查询

Question

我抽象课：

@Entity
@Inheritance(strategy = InheritanceType.JOINED)
public abstract class A {
  ...
}

很少扩展类，如：

@Entity
public class B extends A {
  ...
}

我也有第三个实体：

@Entity
public class C  {

  @OneToOne(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
  private A objectA;
  ...
}

问题是，我如何在C实体存储库中构造Spring Data JPA finder，以仅查询扩展A所需类型的对象？

Answer 1

您可以使用已定义“类型”的鉴别器值的名称

@Entity
@Inheritance(strategy = InheritanceType.JOINED)
@DiscriminatorColumn(name = "type", discriminatorType = DiscriminatorType.STRING)
@Table(name = "abc")
public abstract class Abc {
....

-------------------------------------------

@Query("select a from Abc a where type = ?1")
List<Abc> findByType(String typeValue);