如何同时持久化两个相互关联的对象？

Question

我正在尝试使用新的 JobAdTasks 对象列表来保存一个新的 JobAdvertise 对象。广告包含与其相关的任务，两者同时成功持久化。但是，每个 JobAdTask 的外键是空的。如何解决这个问题，在双向映射关系中同时持久化两个对象？

JobAdvertise class:

@JsonManagedReference
@OneToMany(cascade = CascadeType.ALL,mappedBy = "jobAdvertise")
private List<JobAdTask> taskList = new ArrayList<>();

public void addTask(JobAdTask adTask) {
   if (adTask != null) {
      if (taskList == null) { taskList = new ArrayList<>(); }
      taskList.add(adTask);
   }
}

JobAdTask class:

@JsonBackReference
@ManyToOne(cascade = {CascadeType.PERSIST, CascadeType.DETACH, CascadeType.MERGE, CascadeType.REFRESH}, fetch = FetchType.LAZY)
@JoinColumn(name = "job_add_id")
private JobAdvertise jobAdvertise;

JobAdvertiseService 服务 class:

JobAdvertise jobAdvertise = new JobAdvertise();

for (String task : jobAdCreation.getTaskList()) {
   JobAdTask jobAdTask = new JobAdTask();
   jobAdTask.setTask(task);
   jobAdTaskRepo.save(jobAdTask);
   
   //Relationship JobAdvertise and JobAdTask
   jobAdvertise.addTask(jobAdTask);
}

jobAdvertiseRepo.save(jobAdvertise);

Answer 1

在您的服务中，您需要更改为以下内容：

for (String task : jobAdCreation.getTaskList()) {
   JobAdTask jobAdTask = new JobAdTask();
   jobAdTask.setTask(task);
   jobAdTask.setJobAdvertise(jobAdvertise);
   jobAdTask = jobAdTaskRepo.save(jobAdTask); // Also re-assign the jodAdTask variable since otherwise the id and any timestamps managed by the ORM won't be available in your object.
   
   //Relationship JobAdvertise and JobAdTask
   jobAdvertise.addTask(jobAdTask);
}

一个选项是re-write代码如下：

// in JobAdvertise
public void addTask(JobAdTask adTask) {
   if (adTask != null) {
      adTask.setJobAdvertise(this); // Link the objects here
      if (taskList == null) { taskList = new ArrayList<>(); }
      taskList.add(adTask);
   }
}

public void addTasks(Collection<JobAdTask> adTasks) { // add this method to enable passing a collection to the object, removing the need for iteration from the service class.
   adTasks.forEach(this::addTask);
}

// in JobAdTask create a constructor taking a string

public JobAdTask(String task) {
   this.setTask(task);
}

// in JobAdvertiseService
List<JobAdTask> jobAdTasks = jobAdCreation.getTaskList().stream().map(JobAdTask::new).collect(Collectors.toList()); // creates list of jobAdTasks using the constructor taking a String argument

JobAdvertise jobAdvertise = new JobAdvertise();
jobAdvertise.addTasks(jobAdTasks); // the addTasks uses the addTask method of jobAdvertise, which links the JobAdvertise object and each JobAdTask object.
jobAdvertise = jobAdvertiseRepo.save(jobAdvertise); // when you save the JobAdvertise, since you use CascadeType.ALL, both the advertise and each task object will be persisted to the database.

如何同时持久化两个相互关联的对象？

How persist two objects related to each other at the same time?

java

spring-boot

hibernate

hibernate-mapping

在您的服务中，您需要更改为以下内容：

一个选项是re-write代码如下：