The type of field isn't supported by declared persistence strategy "OneToMany"
- by Robert
We are new to JPA and trying to setup a very simple one to many relationship where a pojo called Message can have a list of integer group id's defined by a join table called GROUP_ASSOC. Here is the DDL:
CREATE TABLE "APP"."MESSAGE" (
"MESSAGE_ID" INTEGER NOT NULL GENERATED ALWAYS AS IDENTITY (START WITH 1, INCREMENT BY 1)
);
ALTER TABLE "APP"."MESSAGE" ADD CONSTRAINT "MESSAGE_PK" PRIMARY KEY ("MESSAGE_ID");
CREATE TABLE "APP"."GROUP_ASSOC" (
"GROUP_ID" INTEGER NOT NULL,
"MESSAGE_ID" INTEGER NOT NULL
);
ALTER TABLE "APP"."GROUP_ASSOC" ADD CONSTRAINT "GROUP_ASSOC_PK" PRIMARY KEY ("MESSAGE_ID", "GROUP_ID");
ALTER TABLE "APP"."GROUP_ASSOC" ADD CONSTRAINT "GROUP_ASSOC_FK" FOREIGN KEY ("MESSAGE_ID")
REFERENCES "APP"."MESSAGE" ("MESSAGE_ID");
Here is the pojo:
@Entity
@Table(name = "MESSAGE")
public class Message {
@Id
@Column(name = "MESSAGE_ID")
@GeneratedValue(strategy = GenerationType.IDENTITY)
private int messageId;
@OneToMany(fetch=FetchType.LAZY, cascade=CascadeType.PERSIST)
private List groupIds;
public int getMessageId() {
return messageId;
}
public void setMessageId(int messageId) {
this.messageId = messageId;
}
public List getGroupIds() {
return groupIds;
}
public void setGroupIds(List groupIds) {
this.groupIds = groupIds;
}
}
When we try to execute the following test code we get <openjpa-1.2.3-SNAPSHOT-r422266:907835 fatal user error> org.apache.openjpa.util.MetaDataException: The type of field "pojo.Message.groupIds" isn't supported by declared persistence strategy "OneToMany". Please choose a different strategy.
Message msg = new Message();
List groups = new ArrayList();
groups.add(101);
groups.add(102);
EntityManager em = Persistence.createEntityManagerFactory("TestDBWeb").createEntityManager();
em.getTransaction().begin();
em.persist(msg);
em.getTransaction().commit();
Help!
