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POMapping a java.util.map<entity, entity> in hibernate using JPA annotations
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  1. POMapping a java.util.map<entity, entity> in hibernate using JPA annotations
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    copied!<p>I seem to be having an issue with mapping a collection in hibernate where the key and the resource are both entities to be mapped by hibernate.</p> <p>Whereas from the documentation (my main resource for this issue has been this, but I of course welcome any others: <a href="http://docs.jboss.org/hibernate/orm/3.6/reference/en-US/html/collections.html" rel="nofollow">http://docs.jboss.org/hibernate/orm/3.6/reference/en-US/html/collections.html</a>) it would appear that this should be a relatively simple task, I just can't seem to get the key of the map to persist.</p> <p>My code as it stands looks like this:</p> <p>Parent class:</p> <pre><code>@Entity public class Parent { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private int id; @MapKey @MapKeyClass(Key.class) @ManyToMany(cascade = CascadeType.ALL) private Map&lt;Key, Resource&gt; map; </code></pre> <p>Key class:</p> <pre><code>@Table(name="ParentKey") @Entity public class Key implements Comparable&lt;Key&gt; { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private int id; @Column(name = "hierarchyKey") private int key; </code></pre> <p>The resource class is a relatively simple POJO and persists fine, so I would assume that the issue is not in that class.</p> <p>I did come across the annotation @MapKeyManyToMany in some documentation on the hibernate forums, but I believe this has since been deprecated.</p> <p>The schema of the database is unimportant at this stage, the main concern is simply making sure everything persists to the database. We're using MySQL for the underlying database.</p> <p>As I'm sure you can probably guess, any search involving the words map, hibernate, entity and key return a large amount of questions not related to this issue, though I'm sure this must be a situation that occurs quite often in terms of mapping situations.</p> <p>I don't often submit questions, but I am an active reader, so please let me know if any more info is required.</p>
 

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