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JPA 2 Hibernate映射,在主键中使用带有三层结构的@IdClass

java-ee-6 jpa hibernate java

psychollek · 技术社区 · 11 年前

这个问题非常类似于: JPA (Hibernate, EclipseLink) mapping: why doesn't this code work (chain of 2 relationships using JPA 2.0, @EmbeddedId composite PK-FK)?

实际上,我唯一(从我发现的有意义的地方)的区别是我使用 @IdClass 而且我很可能无法切换到与hibernate不同的提供商。

但无论如何,这里是代码(删除了不重要的部分):

PermissionContextType.java :

@Entity
@IdClass(PermissionContextTypePk.class)
public class PermissionContextType{
   @Id    
   private String id;    

   @Id
   @JoinColumn (name = "PROJECT", referencedColumnName = "ID")
   @ManyToOne ()
   private Project project;

   public static class PermissionContextTypePk implements Serializable{
       public String project;
       public String id;
       // ... eq and hashCode here ...
   }

}

PermissionContext.java :

@Entity
@IdClass(PermissionContextPk.class)
public class PermissionContext{
   @Id
   private String id;

   @Id
   @JoinColumns ({
            @JoinColumn (name = "PROJECT", referencedColumnName = "PROJECT"),
            @JoinColumn (name = "PERMISSIONCONTEXTTYPE", referencedColumnName = "ID")
        })
   @ManyToOne
   private PermissionContextType permissionContextType;

   public static class PermissionContextPk implements Serializable{
      public String id;
      public PermissionContextTypePk permissionContextType;
      // ... eq and hashCode here ...
   }
}

Permission.java :

@Entity
@IdClass(PermissionPk.class)
public class Permission{

   @Id
   private String id;

   @Id
   @JoinColumns ({
            @JoinColumn (name = "PROJECT", referencedColumnName = "PROJECT"),
            @JoinColumn (name = "PERMISSIONCONTEXTTYPE", referencedColumnName = "PERMISSIONCONTEXTTYPE"),
            @JoinColumn (name = "PERMISSIONCONTEXT", referencedColumnName = "ID")
        })
   @ManyToOne
   private PermissionContext permissionContext;

   public static class PermissionPk implements Serializable{
      public String id;        
      public PermissionContextPk permissionContext;
      // ... eq and hashCode here ...
   }
}

我得到的是:

 org.hibernate.AssertionFailure: Unexpected nested component on the referenced entity when mapping a @MapsId: PermissionContext 
    Caused by: org.hibernate.AssertionFailure: org.hibernate.AssertionFailure: Unexpected nested component on the referenced entity when mapping a @MapsId: PermissionContext

是否有人知道这是一个休眠错误,我应该将其发布在他们的问题跟踪系统上(并祈祷我能够更新到给定的休眠版本),或者我绑定实体的方式有什么根本错误?

我已经在EAP6.1(4.2.0)和wildfly(不知道是哪一个)上用hibernate实现检查了它

2 回复 | 直到 9 年前

psychollek 11 年前

好的,这就是我目前所发现的:

谢谢我的朋友: https://hibernate.atlassian.net/browse/HHH-5764 这很可能是这种行为的原因。

我找到了一个解决方法:

许可.java:

@Entity
@IdClass(PermissionPk.class)
public class Permission{

   @Id
   private String id;

// for the next 3 fields there are no public acessors, so the public API of the class was not changed !
   @Id
   @Column(name = "PROJECT")
   private String projectId;

   @Id
   @Column(name = "PERMISSIONCONTEXTTYPE")
   private String permissionContextTypeId;

   @Id
   @Column(name = "PERMISSIONCONTEXT")
   private String permissionContextId;


   @JoinColumns ({
            @JoinColumn (name = "PROJECT", referencedColumnName = "PROJECT", updatable = false, insertable = false),
            @JoinColumn (name = "PERMISSIONCONTEXTTYPE", referencedColumnName = "PERMISSIONCONTEXTTYPE", updatable = false, insertable = false),
            @JoinColumn (name = "PERMISSIONCONTEXT", referencedColumnName = "ID", updatable = false, insertable = false)
        })
   @ManyToOne
   private PermissionContext permissionContext;

   public static class PermissionPk implements Serializable{      
// previously they where private as well, but removed public constructor for the sake of simplicity of the question - so no changes where necesary in public API of the class !
      private String id;        
      private String projectId;        
      private String permissionContextTypeId;
      private String permissionContextId;

   public PermissionPk () {}

    public PermissionPk (String aId, PermissionContextPk aPermissionContext) {
        this.id = aId;
        permissionContextId = aPermissionContext.id;
        permissionContextTypeId = aPermissionContext.permissionContextType.id;
        projectId = aPermissionContext.permissionContextType.project;
    }  
... eq and hashCode here ...
   }
}

这种解决方法的好处是它不会以任何方式更改类的公共API (唯一的变化是,我需要使PermissionPk可以看到上下文和上下文类型Pk中的字段-它们以前是私有的,只有一个公共构造函数(但再次简化了这个问题)),也没有改变jpql查询,同时,解决方法是可扩展的(可以扩展到任何级别-只要每个偶数Pk都不包含另一个Pk),因此,如果这个bug能够得到解决,那么很容易删除解决方法。

我仍然很乐意接受对我的解决方法或问题本身的任何评论。

psychollek 11 年前

今天我找到了另一个解决方法:) 您可以完全省略@IdClass,并使用特定于休眠的功能来动态创建复合键,因为它显然不受此错误的影响。这里的缺点是:

它完全是Hibernate特有的,JPA根本没有涉及。
无法执行em.find(ClassName.class,newClassPk(args…)),因为根本没有ClassPk。

但是,如果你可以使用除休眠之外的任何东西,那么你也可以使用没有这个bug的东西——所以1可能真的不是问题。还有一种可能性是,您实际上不需要这个实体的em.find(或者可以通过会话或jpql查询来创建它)。