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EJB3 inheritance and composite key
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created by <a href="https://community.jboss.org/people/blawrence">Bobby Lawrence</a> in <i>EJB3</i> - <a href="https://community.jboss.org/message/717603#717603">View the full discussion</a>
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<div class="jive-rendered-content"><p>Hoping someone can help.</p><p>I have an app that I'm trying to use EJB3 entities for.</p><p>One entity represents a Person:</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><pre class="jive-pre"><code class="jive-code jive-java">@Entity
@Table (name = <font color="red">"USERS"</font>)
@Inheritance (strategy = InheritanceType.JOINED)
<font color="navy"><b>public</b></font> <font color="navy"><b>class</b></font> Person <font color="navy">{</font>
 
    @Column (name = <font color="red">"PERSON_ID"</font>)
    @Id
    @SequenceGenerator (name = <font color="red">"personIdGenerator"</font>, allocationSize = 1, sequenceName = <font color="red">"PERSON_SEQ"</font>)
    @GeneratedValue (generator = <font color="red">"personIdGenerator"</font>, strategy = GenerationType.SEQUENCE)
    <font color="navy"><b>private</b></font> <font color="navy"><b>long</b></font> id;
 
   @Column (name = <font color="red">"EMAIL"</font>)
   <font color="navy"><b>private</b></font> String email;
   
    @Column (name = <font color="red">"FIRSTNAME"</font>)
    <font color="navy"><b>private</b></font> String firstName;
   
   @Column (name = <font color="red">"LASTNAME"</font>)
   <font color="navy"><b>private</b></font> String lastName;
 
   ...
<font color="navy">}</font>
</code></pre><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>Now I have another entity called PrimaryInvestigator that extends Person so I can use the email, lastname, firstname attributes.  However the db table for this entity has a composite key representing the person's id and the project the person is associated with: projectId.  So this entity requires a composite key.  :</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><pre class="jive-pre"><code class="jive-code jive-java">@Entity
@IdClass (PrimaryInvestigatorPK.class)
@Table (name = <font color="red">"PROJECT_PI"</font>)
<font color="navy"><b>public</b></font> <font color="navy"><b>class</b></font> PrimaryInvestigator <font color="navy"><b>extends</b></font> Person <font color="navy">{</font>
 
    @Column (name = <font color="red">"PROJECT_ID"</font>, insertable=false, updatable=<font color="navy"><b>false</b></font>)
    @Id
    <font color="navy"><b>private</b></font> <font color="navy"><b>long</b></font> projectId;
 
    @Column (name = <font color="red">"BIOSKETCH_FILE_ID"</font>)
    <font color="navy"><b>private</b></font> <font color="navy"><b>long</b></font> biosketchFileId;
    ...
<font color="navy">}</font>
</code></pre><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>My IdClass for the PrimaryInvestigator entity looks like this:</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><pre class="jive-pre"><code class="jive-code jive-java"><font color="navy"><b>public</b></font> <font color="navy"><b>class</b></font> PrimaryInvestigatorPK <font color="navy"><b>implements</b></font> Serializable <font color="navy">{</font>
 
  <font color="navy"><b>public</b></font> Long userId;
  <font color="navy"><b>public</b></font> Long projectId;
 
  ...
<font color="navy">}</font>
</code></pre><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>Since part of the composite key is in the Person superclass, I figured I could just add another @Id attribute representing the other part of the composite key and Hibernate would simply use the combination of the two in my composite key.</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>However, every time I try to deploy the EJBs, I get the following exception:</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><pre class="jive-pre"><code class="jive-code jive-java"> org.hibernate.AnnotationException: Unable to define/override @Id(s) on a subclass: org.jlab.mis.apps.mics.valueobjects.PrimaryInvestigator
</code></pre><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>Is what I'm trying to do possible?  If so how?  </p><p>I can't use a @MappedSuperclass because I need to be able to persist Person objects by themselves...</p><p>Any ideas?</p></div>
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<p style="margin: 0;">Start a new discussion in EJB3 at <a href="https://community.jboss.org/choose-container!input.jspa?contentType=1&containerType=14&container=2029">Community</a></p>
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