使用JoinTable进行JPA自我联接

问题描述

我有1个实体调用项，我希望在其中将父项链接到子项.使用联接表创建父/子关系.我还没有得到任何好的文档.因此，如果有人有任何想法，我都会耳熟能详.

I have 1 entity call Item in which I want to be able to link parent items to children. to use a join table to create a parent/child relationship. I haven't been able to get any good documentation on. So if anyone has any thoughts I'm all ears.

这是我所拥有的...大部分时间都有效.

Here is what I have... which works most of the time.

public class Item implements java.io.Serializable {
     @Id
     private Long id;

     @ManyToOne(optional = true, fetch = FetchType.LAZY)
     @JoinTable(name = "ITEMTOITEM", joinColumns = { @JoinColumn(name = "ITEMID") }, inverseJoinColumns = { @JoinColumn(name = "PARENTITEMID") } )
     private Item parent;

     @OneToMany(mappedBy = "parent", fetch = FetchType.LAZY)
     private List<Item> children;
}

有时我想带回绑定到该项目表的对象时，出现以下错误:

At times when I want to bring back objects that are tied to this item table I am getting an error of the following:

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.springframework.webflow.engine.ActionExecutionException: Exception thrown executing [AnnotatedAction@6669ff5 targetAction = com.assisted.movein.web.common.nav.NavAction@6edf74b7, attributes = map['method' -> 'handleEntry']] in state 'oneTimeChargesAndFeesView' of flow 'in-flow' -- action execution attributes were 'map['method' -> 'handleEntry']'; nested exception is Exception [TOPLINK-4002] (Oracle TopLink Essentials - 2.0.1 (Build b04-fcs (04/11/2008))): oracle.toplink.essentials.exceptions.DatabaseException
Internal Exception: java.sql.SQLException: ORA-00904: "PARENTITEM_ITEMID": invalid identifier

 Error Code: 904
 Call: SELECT ITEMID, ITEMSHORTDESC, EFFENDDATE, ITEMDESC, PARENTITEM_ITEMID,  ITEMTYPECODE FROM ITEM WHERE (ITEMID = ?)
    bind => [1250]
Query: ReadObjectQuery(com.domain.Item)

任何帮助将不胜感激.

推荐答案

在对JPA 2.0进行了大量阅读之后，我发现我需要一个较新版本的Eclipselink 2.3+才能支持我想做的事情.这是在我的情况下实际有效的代码，但是由于我们对较早版本[EclipseLink 2.0.2]的依赖，因此无法使用.同样，另一个项目仍在使用Toplink-essentials JPA 1.0，它再次喜欢这种表示法.

After a lot of reading on JPA 2.0 I figured out that I needed a newer version of Eclipselink 2.3+ in order to support what I was trying to do. Here is the code that actually worked in my case, but it will not work due to our dependency on an older version [EclipseLink 2.0.2]. Also another project's is still using Toplink-essentials JPA 1.0 which again does like this notation.

public class Item {

@ManyToOne(optional = true, fetch = FetchType.LAZY)
@JoinTable(name = "ITEMINCENTIVESMAPPING",
        joinColumns = { @JoinColumn(name = "INCENTIVEITEMID", referencedColumnName = "ITEMID", insertable = false, updatable = false) },
        inverseJoinColumns = { @JoinColumn(name = "ITEMID", referencedColumnName = "ITEMID", insertable = false, updatable = false) } )
private Item parentItem;

@OneToMany(fetch = FetchType.LAZY)
@JoinTable(name = "ITEMINCENTIVESMAPPING",
        joinColumns = { @JoinColumn(name = "INCENTIVEITEMID", referencedColumnName = "ITEMID") },
        inverseJoinColumns = { @JoinColumn(name = "ITEMID", referencedColumnName = "ITEMID") } )
private List<Item> items;

}

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