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POThe type of field isn't supported by declared persistence strategy "OneToMany"
 

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    <p>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 <code>GROUP_ASSOC</code>. Here is the DDL:</p> <pre>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");</pre> <p>Here is the pojo:</p> <pre><code>@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; } }</code></pre> <p>I know this is wrong as there is no <code>@Column</code> mapping to <code>GROUP_ASSOC.GROUP_ID</code> for the groupIds property, but hopefully this illustrates what we are trying to do. When we run the following test code we get <code>&lt;openjpa-1.2.3-SNAPSHOT-r422266:907835 fatal user error&gt; 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.</code></p> <pre><code>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();</code></pre> <p>Help!</p>
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