如何使用JPA关系实体创建RestAPI
如何使用JPA关系实体创建RestAPI
提问于 2018-09-26 23:06:31
我有个问题。当我有其他实体时，我不知道如何创建API。我使用Postman，当我请求查看数据库中的所有项目时，我也希望接收实体。
例如，这是我的实体：
@Entity
@Table(name = "project")
public class Project {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "proj_id")
private int projectId;
@Column(name = "project_name")
private String projectName;
@Column(name = "dg_number")
private int dgNumber;
@ManyToMany
@JoinTable(name = "project_gate_relation", joinColumns = @JoinColumn(name = "proj_id"), inverseJoinColumns = @JoinColumn(name = "gate_id"))
@JsonBackReference
private List<Gate> gates;
@ManyToMany
@JoinTable(name = "project_threshold_relation", joinColumns = @JoinColumn(name = "proj_id"), inverseJoinColumns = @JoinColumn(name = "thresholdgates_id"))
@JsonBackReference
private List<Threshold> thresholds;这是Gate实体
@Entity
@Table(name = "gate")
public class Gate {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "gate_id")
private int gateId;
@Column(name = "gate_type")
private String gateType;
@Column(name = "gate_value")
private float value;阈值实体
@Entity
@Table(name = "threshold")
public class Threshold {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "threshold_id")
private int thresholdId;
@Column(name = "threshold_value")
private int thresholdValue;
@Column(name = "threshold_type")
private String thresholdType;控制器
@RestController
@RequestMapping(ProjectController.PROJECT_URL)
public class ProjectController {
public static final String PROJECT_URL = "/cidashboard/projects";
@Autowired
private final ProjectService projectService;
public ProjectController(ProjectService projectService) {
this.projectService = projectService;
}
@GetMapping
public List<Project> getAllProjects(){
return projectService.findAllProjects();
}
@GetMapping("/{id}")
public Project getProjectById(@PathVariable int id) {
return projectService.findProjectById(id);
}
@PostMapping
// @Consumes(MediaType.APPLICATION_JSON_VALUE)
public Project saveProject(@RequestBody Project newProj) {
return projectService.saveProject(newProj);
}
}当我在Postman中执行Get请求时，我收到以下输出，例如：
{
"projectId": 1,
"projectName": "jenkins",
"dgnumber": 1
}, 我希望能收到关于gate和threshold的信息。我不知道如何更准确地做这些事情。
回答 1
Stack Overflow用户
回答已采纳
发布于 2018-09-26 23:19:03
默认情况下，与@ManyToMany关联的数据是延迟加载的。您需要指定您希望立即加载(如果您使用的是spring-data，则可以使用实体图)。
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原文链接：
https://stackoverflow.com/questions/52520910
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