我是 Spring Boot 新手。我有一个 mysql 数据库,我使用查询来计算表中的行数。但这不起作用,它仍然返回我原来的表数据。你能帮我检查一下我的代码吗?
这是我的实体:
@Entity
@Table(name = "act_id_membership", schema = "activiti", catalog = "")
@IdClass(ActIdMembershipEntityPK.class)
public class ActIdMembershipEntity {
private String userId;
private String groupId;
@Id
@Column(name = "USER_ID_")
public String getUserId() {
return userId;
}
public void setUserId(String userId) {
this.userId = userId;
}
@Id
@Column(name = "GROUP_ID_")
public String getGroupId() {
return groupId;
}
public void setGroupId(String groupId) {
this.groupId = groupId;
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
ActIdMembershipEntity that = (ActIdMembershipEntity) o;
return Objects.equals(userId, that.userId) &&
Objects.equals(groupId, that.groupId);
}
@Override
public int hashCode() {
return Objects.hash(userId, groupId);
}
}
这是我的询问:
@Repository
public interface MemershipRepository extends JpaRepository<ActIdMembershipEntity, String> {
@Query ("select new com.example.activiti_restful.dtos.UserMembership(i.userId, count(i)) from ActIdMembershipEntity i where i.userId ='kermit'")
UserMembership countMemberships(String userId);
}
更新代码: 我的服务等级:
@Service
public class MembershipService {
@Autowired
private MemershipRepository repository;
public long count() {
return repository.count();
}
我的资源类:
@RestController
public class MembershipResource {
@Autowired
private MembershipService membershipService;
@GetMapping("/membership")
public long list() {return membershipService.count();}
}
我的自定义 JSON 对象类:
public class UserMembership {
private String userId;
private long numberOfusers;
public UserMembership(String userId, long numberOfusers) {
this.userId = userId;
this.numberOfusers = numberOfusers;
}
}
根据 存储库文档,使用
CrudRepository
提供了一种名为 count() 的方法,它是实现 JpaRepository
的 Superinterfaces之一。
基于 CrudRepository 文档 说:
长计数();返回实体的数量。
那么你应该使用
CrudRepository
方法。另外删除大写MembershipREPOSITORY,根据java代码约定,你必须通过以下方式使用MembershipRepository。
@Repository
public interface MembershipRepository extends JpaRepository <ActIdMembershipEntity, String> {
}
并在您的服务中使用它:
@Service
public class MembershipService {
@Autowired
private MembershipRepository repo;
public long count() {
return repo.count();
}
}
已更新
根据您的要求: 在控制器中:
@RestController
public class MembershipResource {
@Autowired
private MembershipService membershipService;
@GetMapping("/membership")
public List<Object> list() { return membershipService.countMemberships();
}
}
服务中:
@Service
public class MembershipService {
@Autowired
private MemershipRepository repository;
public List<Object> countMemberships() {
return repository.countMemberships();
}
}
在存储库中:
@Repository
public interface MemershipRepository extends JpaRepository<ActIdMembershipEntity, String> {
@Query ("select i.userId, count(i) from ActIdMembershipEntity i where i.userId ='kermit'")
List<Object> countMemberships();
}
*> 实际上我希望它返回一个像 [{ name: kermit, value:6}] 这样的 json 格式。现在它只返回数字 6。我怎样才能做到这一点?谢谢!
首先,创建一个类来包装您的数据:
public class UserMembership {
private String userId;
private long numberOfUsers;
public UserMembership(String userId, long numberOfUsers) {
this.userId = userId;
this.numerOfUsers = numberOfUsers;
}
}
然后
@Repository
public interface MembershipRepository extends JpaRepository <ActIdMembershipEntity, String> {
@Query ("select new *****.UserMembership(i.userId, count(i)) from ActIdMembershipEntity i where i.userId = :userId")
UserMembership countMemberships(String userId);
}
*****:您的完整包名称
希望有帮助!