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POHibernate ManyToMany does not work when using Inheritance
 

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  1. POHibernate ManyToMany does not work when using Inheritance
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    <p>I just refactor a Project to use Hibernate (4.2.4.Final) with Inheritance. But I got trouble with ManyToMany annotation.</p> <p>I have a base File Class like this:</p> <pre><code>@Entity @Table(name = "file") @Inheritance(strategy = InheritanceType.SINGLE_TABLE) @DiscriminatorColumn(name = "descriminator", length = 25) public abstract class File { @Id @Column(name = "id", unique = true, nullable = false, length = 256) private String id; } </code></pre> <p>and a special Inheritance class like this: </p> <pre><code>@Entity @DiscriminatorValue("ISSUE_HISTORY_ATTACHMENT") @Data public class IssueHistoryAttachment extends File { @ManyToOne(fetch = FetchType.LAZY) @JoinTable(name = "issue_history_attachment", joinColumns = { @JoinColumn(name = "attachment_id", nullable = false, unique = true) }, inverseJoinColumns = { @JoinColumn(name = "issue_history_id", nullable = false)}) private IssueHistory history; } </code></pre> <p>This IssueHistoryAttachment Class is also referenced in my IssueHistory Class.</p> <pre><code>@Entity @Table(name = "issue_history") @TableGenerator(name="tg", table="hibernate_sequences",pkColumnName="sequence_name", valueColumnName="sequence_next_hi_value", allocationSize=1) public class IssueHistory implements java.io.Serializable { @Id @GeneratedValue(strategy = GenerationType.TABLE, generator = "tg") @Column(name = "id", unique = true, nullable = false) private int id; // some other fields @ManyToMany(fetch = FetchType.LAZY) @JoinTable(name = "issue_history_attachment", joinColumns = { @JoinColumn(name = "issue_history_id", nullable = false) }, inverseJoinColumns = { @JoinColumn(name = "attachment_id", nullable = false, unique = true) }) private Set&lt;IssueHistoryAttachment&gt; attachments = new HashSet&lt;IssueHistoryAttachment&gt;(); } </code></pre> <p>When i now store a IssueHistory Instance with two Attachments, all this fields are correctly saved in my database.</p> <p>I got 2 new entries in the <em>file</em> table, one new entry in the *issue_history* table and two correct entries in the relation table *issue_history_attachment*.</p> <p>So at this points all thinks are looking fine. But when I try to read the Values Attachment Set in the IssueHistory Instance <strong>only contains one element instead of two</strong> like stored in the database.</p> <p>Any suggestions how to solve this?</p>
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