Question

I tried various things, e.g. most simple:

// 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
}

but this produces the error:

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)

Any idea?

I am using latest 2.4.1-SNAPSHOT on Glassfish 3.1.2.

Solution

Add the @MapKey annotation and choose the desired key field within your embeddable class:

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

Answer 1

You should be able to use a @MapKey to define the map key from the Attribute object (I assume its name).

@MapKeyColumn, @MapKeyJoinColumn and @MapKeyClass are not supported by EclipseLink’s current NoSQL support.

Please log a bug about the exception though, you should get a better error, or the map key should be defaulted better.