我使用的是Spring启动应用程序,并且存在以下2个实体。
person.Java
@Entity
@Data
@EqualsAndHashCode(callSuper = true)
@AllArgsConstructor
@NoArgsConstructor
@Table(name = "PERSON")
public class Person extends BaseEntity {
@NotNull
@Enumerated(EnumType.STRING)
private StatusType status;
@JsonIgnore
@ManyToMany(fetch = FetchType.EAGER)
@JoinTable(
name = "PERSON_ADDRESS",
joinColumns = @JoinColumn(
name = "person_id", referencedColumnName = "id"),
inverseJoinColumns = @JoinColumn(
name = "address_id", referencedColumnName = "id"))
private Collection<Info> addresses;
}
address.Java
@Entity
@Data
@EqualsAndHashCode(callSuper = true)
@AllArgsConstructor
@NoArgsConstructor
@Table(name = "ADDRESS")
public class Address extends BaseEntity {
@NotNull
private String address;
@ManyToMany(mappedBy = "addresses")
private Collection<Person> persons;
}
我使用JpaRepository
如下。
@Repository
public interface PersonRepository extends JpaRepository<Person, Long> {
}
我使用以下语句来实现分页和排序。
Page<Person> allPersons = personRepository.findAll(pageable);
其中pageable
是org.springframework.data.domain.Pageable
的一个例子。
我可以使用Person
中的其他列进行排序。但我想基于地址集合进行排序,基于每个Address
实体的Person
记录的数量。
简而言之,我想根据Collection的集合大小对Persons进行排序。排序顺序(ASC或DESC)来自前端。
知道Pageable
对象应该如何实现这个吗?如果Person
存在多个Address
,也没有返回任何重复的Person
记录。
根据Order by count using Spring Data JpaRepository,这是解决方案。
在我的实验中,我尝试按如下方式定义Repository,但是存在问题;因为我们在PersonRepository
上定义查询,以便根据addressCount进行排序,弹出数据会查看Person。
@Repository
public interface PersonRepository extends JpaRepository<Person, Long> {
@Query(
value = "select p from Person p join p.addresses ad group by p",
countQuery = "select count(p) from Person p"
)
Page <Person> findAllWithAddressCount(Pageable pageable);
}
因此,作为一种解决方法,我尝试将排序逻辑转换为查询定义本身,最终我为ASC和DESC模式提供了两个版本:
@Repository
public interface PersonRepository extends JpaRepository <Person, Long> {
@Query(
value = "select p from Person p join p.addresses ad group by p Order By addressCount asc",
countQuery = "select count(p) from Person p"
)
Page<Person> findAllOrderByAddressCountAsc(Pageable pageable);
@Query(
value = "select p from Person p join p.addresses ad group by p Order By addressCount desc",
countQuery = "select count(p) from Person p"
)
Page<Person> findAllOrderByAddressCountDesc(Pageable pageable);
}
希望这可以帮助。