一对多映射到超类的属性 [英] one to many mapping to a property of superclass

问题描述

我有一个超类问题及其子类 MultipleChoiceQuestions

超类有一个字段 activity

我想要创建 Set< MultipleChoiceQuestions> ; 并使用 OneToMany 注释使用 mappedBy =activity

例如

  @OneToMany（fetch = FetchType.EAGER，cascade = CascadeType.ALL，mappedBy =activity）
 private Set< NQIMultipleChoiceQuestions> mcqQuestions = new HashSet< NQIMultipleChoiceQuestions>（）; 
  

我得到这个错误：

 org.hibernate.AnnotationException：mappedBy引用未知的目标实体属性
  

然而，如果我创建了一组超类实体，它可以正常工作，例如

  $ b 
 code> @OneToMany（fetch = FetchType.EAGER，cascade = CascadeType.ALL，mappedBy =activity）
 private Set< NQIQuestions> questions = new HashSet< NQIQuestions>（）; 
  

有没有办法映射到超类的属性？

？在OneToMany定义中。

例如..

  @OneToMany （fetch = FetchType.EAGER，cascade = CascadeType.ALL，mappedBy =activity，targetEntity = NQIQuestions.class）
 private Set< NQIMultipleChoiceQuestions> mcqQuestions = new HashSet< NQIMultipleChoiceQuestions>（）; 
  

I have a superclass Questions and its subclass MultipleChoiceQuestions

Superclass has a field activity

I want to create a Set<MultipleChoiceQuestions> and use OneToMany annotation using mappedBy = "activity"

e.g.

@OneToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL, mappedBy = "activity" )
private Set<NQIMultipleChoiceQuestions> mcqQuestions = new HashSet<NQIMultipleChoiceQuestions>();

I am getting this error:

org.hibernate.AnnotationException: mappedBy reference an unknown target entity property 

However, it works fine if I create a set of superclass entities,

e.g.

@OneToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL, mappedBy = "activity")
private Set<NQIQuestions> questions = new HashSet<NQIQuestions>();

Is there a way to map to property of superclass?

解决方案

Found the solution for this... :)

We can achieve this just by defining the targetEntity = ? in the OneToMany definition..

eg..

@OneToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL, mappedBy = "activity" , targetEntity=NQIQuestions.class)    
private Set<NQIMultipleChoiceQuestions> mcqQuestions = new HashSet<NQIMultipleChoiceQuestions>();

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