如何使用Hibernate Criteria查询具有String集合中值的对象？ [英] How do I query for objects with a value in a String collection using Hibernate Criteria?

问题描述

假设Student是包含ComputerScienceStudent和ITStudent的继承层次结构中的父类。学生定义一个名为favoriteColors的字段，它是一个值类型的字符串集合。使用标准API，我想查询所有列出蓝色作为他们最喜欢的颜色之一的学生。

以下是相关的java片段

  @Entity 
 @Inheritance（strategy = InheritanceType.SINGLE_TABLE）
抽象类Student {
 
 @CollectionOfElements 
 Set< String> favoriteColors = new TreeSet< String>（）; 
  

我查看了 http://docs.jboss.org/hibernate/core/3.3/reference/en/html/querycriteria.html 看起来像这样的东西可能是一个开始

  List students = sess.createCriteria（Student.class） 
 .createCriteria（favoriteColors）
 .add（Restrictions.eq（??????，blue））
 .list（）; 
  

但是我不知道要填写什么属性名称，因为String不是我定义的类（因此??????）

我真的想避免使用HQL，除非绝对没有办法使用标准来做到这一点。我也想避免添加sqlRestrictions。我不认为示例API会起作用，因为Student是继承层次结构中的抽象父类，并且我无法创建具体的学生作为示例传入。

<这可能吗？感谢您的时间！

解决方案

您是否尝试过写作

<$ p $ （学生类）
.add（Restrictions.eq（favoriteColors，blue））
.list（）;

编辑：好的，那不行。根据这个相关的问题，引用使用Criteria API，价值型集合的元素目前是不可能的。

Let's say Student is the parent class in an inheritance hierarchy that includes ComputerScienceStudent and ITStudent. Student defines a field called favoriteColors, which is a value-typed collection of Strings. Using the criteria API I'd like to query for all students who list "blue" as one of their favoriteColors.

Here is the relevant java snippet

@Entity
@Inheritance(strategy=InheritanceType.SINGLE_TABLE)
abstract class Student {

    @CollectionOfElements
    Set<String> favoriteColors = new TreeSet<String>();

I looked at the hibernate documentation found at http://docs.jboss.org/hibernate/core/3.3/reference/en/html/querycriteria.html and it looks like something like this might be a start

List students = sess.createCriteria(Student.class)
.createCriteria("favoriteColors")
    .add( Restrictions.eq(??????, "blue") )
.list();

but I don't know what to fill in as the name of the property since String is not a class I defined (thus the ??????)

I'd really like to avoid using HQL unless there is absolutely no way to do this using criteria. I'd also like to avoid adding sqlRestrictions. I don't think the example API will work because Student is the abstract parent class in an inheritance hierarchy and I can't create a concrete Student to pass in as an example.

Is this possible? Thanks for your time!

解决方案

Have you tried writing

List students = sess.createCriteria(Student.class)
.add(Restrictions.eq("favoriteColors", "blue") )
.list();

Edit: Ok, that doesn't work. According to this related question, refering to elements of value-type collections is currently impossible using the Criteria API.

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