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| <li>Summary: </li> |
| <li>Field | </li> |
| <li><a href="#annotation.type.required.element.summary">Required</a> | </li> |
| <li>Optional</li> |
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| <li>Detail: </li> |
| <li>Field | </li> |
| <li><a href="#annotation.type.element.detail">Element</a></li> |
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| <div class="subTitle">org.eclipse.persistence.annotations</div> |
| <h2 title="Annotation Type ClassExtractor" class="title">Annotation Type ClassExtractor</h2> |
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| <pre><a href="https://docs.oracle.com/javase/8/docs/api/java/lang/annotation/Target.html?is-external=true" title="class or interface in java.lang.annotation">@Target</a>(<a href="https://docs.oracle.com/javase/8/docs/api/java/lang/annotation/Target.html?is-external=true#value--" title="class or interface in java.lang.annotation">value</a>=<a href="https://docs.oracle.com/javase/8/docs/api/java/lang/annotation/ElementType.html?is-external=true#TYPE" title="class or interface in java.lang.annotation">TYPE</a>) |
| <a href="https://docs.oracle.com/javase/8/docs/api/java/lang/annotation/Retention.html?is-external=true" title="class or interface in java.lang.annotation">@Retention</a>(<a href="https://docs.oracle.com/javase/8/docs/api/java/lang/annotation/Retention.html?is-external=true#value--" title="class or interface in java.lang.annotation">value</a>=<a href="https://docs.oracle.com/javase/8/docs/api/java/lang/annotation/RetentionPolicy.html?is-external=true#RUNTIME" title="class or interface in java.lang.annotation">RUNTIME</a>) |
| public @interface <span class="memberNameLabel">ClassExtractor</span></pre> |
| <div class="block">A ClassExtractor allows for a user defined class indicator in place of |
| providing a discriminator column. The class has the following restrictions: |
| <ul> |
| <li> It must extend the org.eclipse.persistence.descriptors.ClassExtractor |
| class and implement the extractClassFromRow(Record, Session) method. |
| <li> That method must take a database row (a Record/Map) as an argument and |
| must return the class to use for that row. |
| </ul> |
| This method will be used to decide which class to instantiate when reading |
| from the database. It is the application's responsibility to populate any |
| typing information in the database required to determine the class from the |
| row. |
| <p> |
| The ClassExtractor must only be set on the root of an entity class or |
| sub-hierarchy in which a different inheritance strategy is applied. The |
| ClassExtractor can only be used with the SINGLE_TABLE and JOINED inheritance |
| strategies. |
| <p> |
| If a ClassExtractor is used then a DiscriminatorColumn cannot be used. A |
| DiscriminatorColumn also cannot be used on either the root or its subclasses. |
| <p> |
| In addition, for more complex configurations using a ClassExtractor and a |
| SINGLE_TABLE strategy, the descriptor's withAllSubclasses and onlyInstances |
| expressions should be set through the ClassExtractor's initialize method.</div> |
| <dl> |
| <dt><span class="seeLabel">See Also:</span></dt> |
| <dd><a href="../../../../org/eclipse/persistence/descriptors/ClassExtractor.html" title="class in org.eclipse.persistence.descriptors"><code>ClassExtractor</code></a>, |
| <a href="../../../../org/eclipse/persistence/descriptors/InheritancePolicy.html#setWithAllSubclassesExpression-org.eclipse.persistence.expressions.Expression-"><code>InheritancePolicy.setWithAllSubclassesExpression(Expression)</code></a>, |
| <a href="../../../../org/eclipse/persistence/descriptors/InheritancePolicy.html#setOnlyInstancesExpression-org.eclipse.persistence.expressions.Expression-"><code>InheritancePolicy.setOnlyInstancesExpression(Expression)</code></a></dd> |
| <dt><span class="simpleTagLabel">Author:</span></dt> |
| <dd>Guy Pelletier</dd> |
| <dt><span class="simpleTagLabel">Since:</span></dt> |
| <dd>EclipseLink 2.1</dd> |
| </dl> |
| </li> |
| </ul> |
| </div> |
| <div class="summary"> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <!-- =========== ANNOTATION TYPE REQUIRED MEMBER SUMMARY =========== --> |
| <ul class="blockList"> |
| <li class="blockList"><a name="annotation.type.required.element.summary"> |
| <!-- --> |
| </a> |
| <h3>Required Element Summary</h3> |
| <table class="memberSummary" border="0" cellpadding="3" cellspacing="0" summary="Required Element Summary table, listing required elements, and an explanation"> |
| <caption><span>Required Elements</span><span class="tabEnd"> </span></caption> |
| <tr> |
| <th class="colFirst" scope="col">Modifier and Type</th> |
| <th class="colLast" scope="col">Required Element and Description</th> |
| </tr> |
| <tr class="altColor"> |
| <td class="colFirst"><code><a href="https://docs.oracle.com/javase/8/docs/api/java/lang/Class.html?is-external=true" title="class or interface in java.lang">Class</a><? extends <a href="../../../../org/eclipse/persistence/descriptors/ClassExtractor.html" title="class in org.eclipse.persistence.descriptors">ClassExtractor</a>></code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../org/eclipse/persistence/annotations/ClassExtractor.html#value--">value</a></span></code> |
| <div class="block">(Required) Defines the name of the class extractor that should be |
| applied to this entity's descriptor.</div> |
| </td> |
| </tr> |
| </table> |
| </li> |
| </ul> |
| </li> |
| </ul> |
| </div> |
| <div class="details"> |
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| <li class="blockList"> |
| <!-- ============ ANNOTATION TYPE MEMBER DETAIL =========== --> |
| <ul class="blockList"> |
| <li class="blockList"><a name="annotation.type.element.detail"> |
| <!-- --> |
| </a> |
| <h3>Element Detail</h3> |
| <a name="value--"> |
| <!-- --> |
| </a> |
| <ul class="blockListLast"> |
| <li class="blockList"> |
| <h4>value</h4> |
| <pre>public abstract <a href="https://docs.oracle.com/javase/8/docs/api/java/lang/Class.html?is-external=true" title="class or interface in java.lang">Class</a><? extends <a href="../../../../org/eclipse/persistence/descriptors/ClassExtractor.html" title="class in org.eclipse.persistence.descriptors">ClassExtractor</a>> value</pre> |
| <div class="block">(Required) Defines the name of the class extractor that should be |
| applied to this entity's descriptor.</div> |
| </li> |
| </ul> |
| </li> |
| </ul> |
| </li> |
| </ul> |
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| <li>Summary: </li> |
| <li>Field | </li> |
| <li><a href="#annotation.type.required.element.summary">Required</a> | </li> |
| <li>Optional</li> |
| </ul> |
| <ul class="subNavList"> |
| <li>Detail: </li> |
| <li>Field | </li> |
| <li><a href="#annotation.type.element.detail">Element</a></li> |
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