如何地圖 <String, EMBEDDABLE> 使用Eclipselink / MongoDB @NoSQL

Question

我嘗試了各種方法，例如最簡單的方法：

// Value object
@Embeddable
@NoSql(dataFormat=DataFormatType.MAPPED)
public class Attribute implements Serializable {

   @Basic
   private String someProp;

   // ... getter/setter omitted
}

@Entity
@NoSql(dataFormat=DataFormatType.MAPPED)
public class FancyEntity implements Serializable {

   @Id
   @GeneratedValue
   @Field(name="_id")
   private String id;

   @ElementCollection
   private Map<String,Attribute> attributes = new HashMap<>();

   // ... getter/setter omitted
}

但這會產生錯誤：

Exception [EclipseLink-28018] (Eclipse Persistence Services - 2.4.1.v20120825fb0a20b): org.eclipse.persistence.exceptions.EntityManagerSetupException
Exception Description: Predeployment of PersistenceUnit [myPersistenceUnit] failed.
Internal Exception: java.lang.ClassCastException: org.eclipse.persistence.eis.mappings.EISCompositeCollectionMapping cannot be cast to org.eclipse.persistence.mappings.foundation.MapComponentMapping
at org.eclipse.persistence.exceptions.EntityManagerSetupException.predeployFailed(EntityManagerSetupException.java:221)
at org.eclipse.persistence.internal.jpa.EntityManagerSetupImpl.createPredeployFailedPersistenceException(EntityManagerSetupImpl.java:1541)
at org.eclipse.persistence.internal.jpa.EntityManagerSetupImpl.predeploy(EntityManagerSetupImpl.java:1532)
at org.eclipse.persistence.jpa.PersistenceProvider.createContainerEntityManagerFactory(PersistenceProvider.java:208)

任何的想法？

我在Glassfish 3.1.2上使用最新的2.4.1-SNAPSHOT。

解

添加@MapKey批注並在可嵌入類中選擇所需的鍵字段：

   @ElementCollection
   @MapKey(name="name")
   private Map<String,Attribute> attributes = new HashMap<>();

Answer 1

您應該可以使用@MapKey從Attribute對象（我假設其名稱）中定義地圖鍵。

EclipseLink當前的NoSQL支持不支持@ MapKeyColumn，@ MapKeyJoinColumn和@MapKeyClass。

但是，請記錄有關該異常的錯誤，您應該得到更好的錯誤，或者應該更好地將map密鑰默認為默認值。