如何获取所有子数据,然后在Spring Boot中进行删除。

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英文:

how to get all child data and then delete in spring boot

问题

以下是翻译好的部分:

我已经按照以下方式映射了一对多关系

    //TourPackage 模型
    @OneToMany(mappedBy = "packages", cascade = CascadeType.ALL, fetch = FetchType.LAZY)
    private Set<Itinerary> itineraries;

    public Set<Itinerary> getItineraries() {
        return itineraries;
    }

在行程模型中

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name="packages_id", nullable = false)
    @OnDelete(action = OnDeleteAction.CASCADE)
    private TourPackage packages;

现在我的更新函数更新表单返回旅行包和多个行程所以我想要做的是删除所有先前的行程并插入新的行程在我写的地方 "//null returned" 据我所知应该返回该套餐的所有行程但返回 null

    @PostMapping("/update-tour-package")
    public String updateTourPackage(@ModelAttribute("tourPackage") TourPackage tourPackage, @RequestParam String[] day, @RequestParam String[] itinerary_title, @RequestParam String[] itinerary_description, @RequestParam String[] itinerary_altitude) {
        
        TourPackage tour = this.tourPackageService.saveTourPackage(tourPackage);

        this.itineraryRepo.deleteAll(tour.getItineraries());//null returned for itinerary

        for (int i = 0; i < day.length; i++) {
            Itinerary ite = new Itinerary();
            ite.setPackages(tour);
            ite.setDay(day[i]);
            ite.setTitle(itinerary_title[i]);
            ite.setDescription(itinerary_description[i]);
            ite.setAltitude(itinerary_altitude[i]);
            this.itineraryRepo.save(ite);
        }
        return "redirect:/";
    }

我做得对吗请指导我正确的方向如果需要提供更多上下文请进行评论
英文:

I have mapped one to many as follows

//TourPackage model
@OneToMany(mappedBy = &quot;packages&quot;, cascade = CascadeType.ALL, fetch = FetchType.LAZY)
private Set&lt;Itinerary&gt; itineraries;
public Set&lt;Itinerary&gt; getItineraries() {
return itineraries;
}

in itinerary model

@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name=&quot;packages_id&quot;, nullable = false)
@OnDelete(action = OnDeleteAction.CASCADE)
private TourPackage packages;

now my update function, update form returns tourPackage and multiple itinerary, so what I want to do is delete all previous itinerary and insert new ones. Where I have written //null returned to my knowledge should return all the itinerary of that package but returns null.

@PostMapping(&quot;/update-tour-package&quot;)
public String updateTourPackage(@ModelAttribute(&quot;tourPackage&quot;) TourPackage tourPackage, @RequestParam String[] day, @RequestParam String[] itinerary_title, @RequestParam String[] itinerary_description, @RequestParam String[] itinerary_altitude) {
TourPackage tour = this.tourPackageService.saveTourPackage(tourPackage);
this.itineraryRepo.deleteAll(tour.getItineraries());//null returned for itinerary
for (int i = 0; i &lt; day.length; i++) {
Itinerary ite = new Itinerary();
ite.setPackages(tour);
ite.setDay(day[i]);
ite.setTitle(itinerary_title[i]);
ite.setDescription(itinerary_description[i]);
ite.setAltitude(itinerary_altitude[i]);
this.itineraryRepo.save(ite);
}
return &quot;redirect:/&quot;;
}

am I doing it right? please point me in right direction. Please comment if I should provide more context to the question.

答案1

得分: 1

因为除非您在其他地方有配置来设置现有的TourPackage作为模型对象,否则@ModelAttribute("tourPackage") TourPackage tourPackage将是一个新实例。

如果您想要修改现有实例,则通过带有ID的隐藏字段发送,并在您的控制器中添加一个方法:

@ModelAttribute
public TourPackage getTourPackage(@RequestParam(name = "tourPckageId", required = false) Long id){
   //如果id不为空,则从repo加载,否则创建新实例
}

现在,updateTourPackage方法将接收上述方法返回的现有实例。

链接:https://docs.spring.io/spring/docs/current/spring-framework-reference/web.html#mvc-ann-methods

英文:

Because unless you have config elsewhere to set an existing TourPackage as the model object, @ModelAttribute(&quot;tourPackage&quot;) TourPackage tourPackage will be a new instance.

If you want to modify an existing instance then send through a hidden field with the ID and add a method inn your controller:

@ModelAttribute
public TourPackage getTourPackage(@RequestParam(name = &quot;tourPckageId&quot;, required = false) Long id){
//load from repo if id is not null or otherwise new instance
}

Now the updateTourPackage method will receive the existing instance returned by the above.

https://docs.spring.io/spring/docs/current/spring-framework-reference/web.html#mvc-ann-methods

答案2

得分: 1

你应该像这样更改代码:

@Transactional
public void deleteAll(TourPackage tourPackage) { // 这里有一些参数
  TourPackage tour = this.tourPackageService.saveTourPackage(tourPackage);

   this.itineraryRepo.deleteAll(tour.getItineraries());//对于行程,返回null

   for (int i = 0; i < day.length; i++) {
     // 用你的代码做相同的操作。
    }


}

@PostMapping("/update-tour-package")
public String updateTourPackage(@ModelAttribute("tourPackage") TourPackage tourPackage) {
  tourPacakageService.deleteAll(tourPackage);

}

这是为什么:

  • 你使用了@OneToMany,并且fetchType为Lazy => 当你需要时,itineraries会在稍后获取,只要你在会话或持久性上下文中。
  • 在Spring JPA中,持久性上下文的默认范围是事务。在调用saveTourPackage(tourPackage)之后,事务已经结束。这就是为什么你会得到行程为null的原因。
英文:

You should change code like this:

    @Transactional
public void deleteAll(TourPackage tourPackage) { // Some param here
TourPackage tour = this.tourPackageService.saveTourPackage(tourPackage);
this.itineraryRepo.deleteAll(tour.getItineraries());//null returned for itinerary
for (int i = 0; i &lt; day.length; i++) {
// Do the same with your code.
}
}
@PostMapping(&quot;/update-tour-package&quot;)
public String updateTourPackage(@ModelAttribute(&quot;tourPackage&quot;) TourPackage tourPackage) {
tourPacakageService.deleteAll(tourPackage);
}

Here is why:

  • You set @OneToMany with fetchType is Lazy => itineraries will get latter when you need it as long as you are in a session or persistence context.
  • In spring JPA, the default scope of persistence context is transaction. After you call saveTourPackage(tourPackage) the transaction has end. That why you will get null for it itineraries.

huangapple
  • 本文由 发表于 2020年7月30日 22:12:59
  • 转载请务必保留本文链接:https://go.coder-hub.com/63175064.html
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