Java 如何使用play'处理Set（LinkedHashSet）；s Form.formhelper？

我有下面的场景

@Entity
public class Parent {

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private Long id;

    @Column(name = "name", nullable = false)
    private String name;

    @OneToMany(fetch=FetchType.LAZY, cascade=CascadeType.ALL, mappedBy = "parent", orphanRemoval = true)
    private Set<Child> children = new LinkedHashSet<Child>();
   }
@Entity
public class Child {

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private Long id;

    private String name;

    @ManyToOne(fetch=FetchType.LAZY, optional = false)
    private Parent parent;
}

我不想将LinkedHashSet更改为ArrayList（并将接口从Set更改为List），因为我在同一实体中有另一个OneToMany关系（这将导致org.hibernate.loader.MultipleBagFetchException）

我应该怎么做才能拥有BeanRapperImpl处理集？ 可能吗

编辑： 我使用的JSON是：

非常感谢您的帮助。

---

提前谢谢

您是否也可以发布您试图使用的JSON/表单数据？你真的需要LinkedHashSet吗（只是出于好奇）？我已经更新并包含了JSON结构。。。我使用LinkedHashSet是为了避免行李。。。我不想使用IndexColumn和List来避免行李。。。我更喜欢使用集合。。。我只是想知道是否有可能解析为一个集合。。。谢谢如果您只是发送JSON（假设您有一些API端点），那么您可以只使用JSON类，而不需要任何表单。试试这个：

JsonNode JsonNode=request（）.body（）.asJson（）；debug（jsonNode.toString（））；Parent Parent=Json.fromJson（jsonNode，Parent.class）

在这种情况下，您需要至少为

父类

和

子类

提供setter。我遇到了类似的问题。我使用.ajax（）函数发布Javascript。我必须对我的JSON数据调用JSON.stringify（数据）。

Execution exception[[InvalidPropertyException: Invalid property 'children[0]' of bean class [models.Parent]: Illegal attempt to get property 'child' threw exception; nested exception is org.springframework.beans.InvalidPropertyException: Invalid property 'children[0]' of bean class [models.Parent]: Cannot get element with index 0 from Set of size 0, accessed using property path 'children[0]']]
    at play.api.Application$class.handleError(Application.scala:296) ~[play_2.11-2.3.8.jar:2.3.8]
    at play.api.DefaultApplication.handleError(Application.scala:402) [play_2.11-2.3.8.jar:2.3.8]
    at play.core.server.netty.PlayDefaultUpstreamHandler$$anonfun$3$$anonfun$applyOrElse$4.apply(PlayDefaultUpstreamHandler.scala:320) [play_2.11-2.3.8.jar:2.3.8]
    at play.core.server.netty.PlayDefaultUpstreamHandler$$anonfun$3$$anonfun$applyOrElse$4.apply(PlayDefaultUpstreamHandler.scala:320) [play_2.11-2.3.8.jar:2.3.8]
    at scala.Option.map(Option.scala:146) [scala-library-2.11.5.jar:na]
Caused by: org.springframework.beans.InvalidPropertyException: Invalid property 'children[0]' of bean class [models.Parent]: Illegal attempt to get property 'children' threw exception; nested exception is org.springframework.beans.InvalidPropertyException: Invalid property 'children[0]' of bean class [models.Parent]: Cannot get element with index 0 from Set of size 0, accessed using property path 'children[0]'
    at org.springframework.beans.BeanWrapperImpl.getPropertyValue(BeanWrapperImpl.java:848) ~[spring-beans-4.0.3.RELEASE.jar:4.0.3.RELEASE]
    at org.springframework.beans.BeanWrapperImpl.getNestedBeanWrapper(BeanWrapperImpl.java:571) ~[spring-beans-4.0.3.RELEASE.jar:4.0.3.RELEASE]
    at org.springframework.beans.BeanWrapperImpl.getBeanWrapperForPropertyPath(BeanWrapperImpl.java:548) ~[spring-beans-4.0.3.RELEASE.jar:4.0.3.RELEASE]
    at org.springframework.beans.BeanWrapperImpl.setPropertyValue(BeanWrapperImpl.java:912) ~[spring-beans-4.0.3.RELEASE.jar:4.0.3.RELEASE]
    at org.springframework.beans.AbstractPropertyAccessor.setPropertyValues(AbstractPropertyAccessor.java:82) ~[spring-beans-4.0.3.RELEASE.jar:4.0.3.RELEASE]
Caused by: org.springframework.beans.InvalidPropertyException: Invalid property 'children[0]' of bean class [models.Parent]: Cannot get element with index 0 from Set of size 0, accessed using property path 'children[0]'
    at org.springframework.beans.BeanWrapperImpl.getPropertyValue(BeanWrapperImpl.java:800) ~[spring-beans-4.0.3.RELEASE.jar:4.0.3.RELEASE]
    at org.springframework.beans.BeanWrapperImpl.getNestedBeanWrapper(BeanWrapperImpl.java:571) ~[spring-beans-4.0.3.RELEASE.jar:4.0.3.RELEASE]
    at org.springframework.beans.BeanWrapperImpl.getBeanWrapperForPropertyPath(BeanWrapperImpl.java:548) ~[spring-beans-4.0.3.RELEASE.jar:4.0.3.RELEASE]
    at org.springframework.beans.BeanWrapperImpl.setPropertyValue(BeanWrapperImpl.java:912) ~[spring-beans-4.0.3.RELEASE.jar:4.0.3.RELEASE]
    at org.springframework.beans.AbstractPropertyAccessor.setPropertyValues(AbstractPropertyAccessor.java:82) ~[spring-beans-4.0.3.RELEASE.jar:4.0.3.RELEASE]

{
    "name": "PARENT",
    "children": [
        {
            "name": "test"
        }
    ]
}