为何Spring Boot中Apps与App的JPA Repository无法保存数据？

我正在用Java Spring Boot开发一款基于Roku Dev Tools API的遥控器应用，TelevisionRepository能正常保存实体，但AppsRepository和AppRepository无法保存数据。怀疑和从Roku API（返回XML格式）解析对象属性有关。需求是调用http://{{rokuIPAddress}}:8060/query/apps获取指定电视的安装频道并保存到数据库。

控制器代码 #

// 获取电视应用列表
@GetMapping(path = "/get-apps/{name}")
public ResponseEntity<Apps> getApps(@PathVariable String name) {
    return appsService.getApps(name);
}

服务层代码 #

// 获取电视应用列表
public ResponseEntity<Apps> getApps(String name) {
    Television tele = televisionRepository.findByTelevisionName(name).orElseThrow(() -> new TelevisionNotFoundException());
    log.info(String.format("Requesting apps for %s via: http://%s:8060/query/apps", name, tele.getIpAddress()));
    ResponseEntity<Apps> responseEntity = this.restTemplate.getForEntity("http://" + tele.getIpAddress() + ":8060/query/apps", Apps.class);
    Apps apps = responseEntity.getBody();
    System.out.println(apps.toString());
    for (App app : apps.getApp()) {
        appRepository.save(app);
    }
    appsRepository.save(apps);

    return ResponseEntity.ok(apps);
}

实体类代码 #

App实体 #

@Entity
@XmlAccessorType(XmlAccessType.FIELD)
@XmlRootElement(name = "app")
public class App {

    @Id
    @XmlAttribute(name = "id")
    private String id;

    @XmlAttribute(name = "type")
    private String type;

    @XmlAttribute(name = "version")
    private String version;

    @ManyToOne(fetch = FetchType.LAZY)
    @JsonIgnore
    private Apps apps;
    
    // 构造方法、getter和setter
}

Apps实体 #

@Entity
@XmlRootElement(name = "apps")
@Table(name = "apps")
@XmlAccessorType(XmlAccessType.FIELD)
@JsonIgnoreProperties(ignoreUnknown = true)
public class Apps {

    @Id
    @GeneratedValue
    @Column(name = "id", nullable = false)
    private Long id;

    @OneToMany(mappedBy = "apps", cascade = CascadeType.REMOVE)
    @JacksonXmlElementWrapper(useWrapping = false)
    private List<App> app;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "television_id")
    @JsonIgnore
    private Television television;

    // 构造方法、getter和setter
}

Repository定义 #

AppRepository #

public interface AppRepository extends JpaRepository<App, String> {
}

AppsRepository #

public interface AppsRepository extends JpaRepository<Apps, Long> {
}

H2数据库配置 #

spring.datasource.url=jdbc:h2:mem:testdb
spring.datasource.driverClassName=org.h2.Driver
spring.datasource.username=sa
spring.jpa.database-platform=org.hibernate.dialect.H2Dialect
spring.h2.console.enabled=true

问题原因及解决方法 #

1. 关联关系未维护
   从Roku API解析得到的Apps和App对象之间没有建立双向关联，保存前需手动设置：

   Apps apps = responseEntity.getBody();
   // 建立双向关联
   if (apps.getApp() != null) {
       apps.getApp().forEach(app -> app.setApps(apps));
   }
   

2. 级联配置缺失
   当前Apps的@OneToMany仅配置了删除级联，需添加保存/更新级联类型，这样保存Apps时会自动级联保存关联的App：

   @OneToMany(mappedBy = "apps", cascade = {CascadeType.PERSIST, CascadeType.MERGE, CascadeType.REMOVE})
   @JacksonXmlElementWrapper(useWrapping = false)
   private List<App> app;
   

   修改后无需循环调用appRepository.save(app)，直接保存apps即可。

3. Television关联未设置
   Apps实体关联了Television，但代码中未绑定对应电视对象，需添加：

   apps.setTelevision(tele);
   

   确保外键约束正常。

4. 事务管理
   为服务层getApps方法添加@Transactional注解，避免事务边界问题导致数据未提交：

   @Transactional
   public ResponseEntity<Apps> getApps(String name) {
       // 原有代码逻辑
   }
   

内容的提问来源于stack exchange，提问作者Adriaan Veney