Hibernate 与构造函数的泛型一对多关系

我有一个使用通用一对多关系的实体。不幸的是，lobmok@allargsconstuctor无法映射/强制转换列表使用通配符约束的集合是。。。对于JPA实体来说有些不方便

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请注意，初始创建后，您将永远无法将任何内容插入声明为

list（1）的列表中。“无法设置字段”错误为JPA，它抱怨无法使用反射读取/填充
EducationTranslation
的
id
属性。我非常怀疑这与
教育
的构造函数有关，（2）您确实意识到您将永远无法在声明为
列表的列表中插入任何内容。关于（2）这是因为对象的内存大小未知吗？我认为设置targetEntity会设置内存大小，这是因为泛型是如何工作的。该声明声明声明：“这是扩展了可翻译的
的某种类型的对象列表。”。您不能向这样的列表中插入任何内容，因为编译器不知道列表接受哪种特定类型的对象。如果不强制转换，列表将在分配后变为只读。好吧，我不插入“任何内容”。我的教育翻译是可翻译的。我通过我的流迭代进行了一些转换。是的，您的流管道生成了一个
列表。然后将其分配给
list类型的属性。非常感谢！尤其是狗猫变形者的例子选得非常好，当我意识到我的逻辑错误时，我笑了：D
@OneToMany(
    targetEntity = EducationTranslation.class,
    cascade = CascadeType.ALL,
    fetch = FetchType.LAZY)
private List<? extends Translatable> translationList = new ArrayList<>();


public Education(Long id, Profile profile, Collection<? extends Translatable> translationList) {
    this.id = id;
    this.profile = profile;
    this.translationList = translationList
        .stream()
        .map(x -> new EducationTranslation(x.getId(), x.getCode(), x.getTranslation()))
        .collect(Collectors.toList());
}

Education education = entityManager.find(Education.class, id);
education.getTranslationList().add(new EducationTranslation(...)); // compilation error

List<Dog> dogs = new ArrayList<>(List.of(new Dog())); //just a mutable collection with a Dog inside
List<? extends Animal> someAnimals = dogs; //a list of Dogs is a list of 'a type that extends Animal', so - valid assignment
someAnimals.add(new Cat()); //hey, a Cat does extend Animal, so this should be legal, right?
Dog shapeshifter = dogs.get(1); //...right???

Object obj = "Hello";
obj.length(); // you know obj points to a String, but you assign it to a reference with a more general type, so this call is illegal

interface TranslationHolder {

    List<? extends Translatable> getTranslationList();
}

class Education implements TranslationHolder {

    private List<EducationTranslation> translationList = new ArrayList<>();

    //this getter is a valid implementation for TranslationHolder.getTranslationList()
    public List<EducationTranslation> getTranslationList() {
        return translationList;
    }
}

class ClassThatUsesEducationButOnlyKnowsItAsTranslationHolder  {

   public void execute() {
        TranslationHolder holder = getEducationAsTranslationHolderInSomeIndirectWay();
        holder.getTranslationList(); // this still return a reference to List<? extends Translatable>, NOT List<EducationTranslation>
   }
}