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Java > Open Source Codes > org > hibernate > id > ForeignGenerator


1 package org.hibernate.id;
2
3 import java.io.Serializable JavaDoc;
4 import java.util.Properties JavaDoc;
5
6 import org.hibernate.HibernateException;
7 import org.hibernate.MappingException;
8 import org.hibernate.Session;
9 import org.hibernate.TransientObjectException;
10 import org.hibernate.dialect.Dialect;
11 import org.hibernate.engine.ForeignKeys;
12 import org.hibernate.engine.SessionImplementor;
13 import org.hibernate.type.EntityType;
14 import org.hibernate.type.Type;
15
16 /**
17  * <b>foreign</b><br>
18  * <br>
19  * An <tt>Identifier</tt> generator that uses the value of the id property of an
20  * associated object<br>
21  * <br>
22  * One mapping parameter is required: property.
23  *
24  * @author Gavin King
25  */
26 public class ForeignGenerator implements IdentifierGenerator, Configurable {
27
28     private String JavaDoc propertyName;
29     private String JavaDoc entityName;
30
31     /**
32      * @see org.hibernate.id.IdentifierGenerator#generate(org.hibernate.engine.SessionImplementor, java.lang.Object)
33      */
34     public Serializable JavaDoc generate(SessionImplementor sessionImplementor, Object JavaDoc object)
35     throws HibernateException {
36         
37         Session session = (Session) sessionImplementor;
38
39         Object JavaDoc associatedObject = sessionImplementor.getFactory()
40                 .getClassMetadata( entityName )
41                 .getPropertyValue( object, propertyName, session.getEntityMode() );
42         
43         if ( associatedObject == null ) {
44             throw new IdentifierGenerationException(
45                     "attempted to assign id from null one-to-one property: " +
46                     propertyName
47                 );
48         }
49         
50         EntityType type = (EntityType) sessionImplementor.getFactory()
51             .getClassMetadata( entityName )
52             .getPropertyType( propertyName );
53
54         Serializable JavaDoc id;
55         try {
56             id = ForeignKeys.getEntityIdentifierIfNotUnsaved(
57                     type.getAssociatedEntityName(),
58                     associatedObject,
59                     sessionImplementor
60                 );
61         }
62         catch (TransientObjectException toe) {
63             id = session.save(associatedObject);
64         }
65
66         if ( session.contains(object) ) {
67             //abort the save (the object is already saved by a circular cascade)
68 return IdentifierGeneratorFactory.SHORT_CIRCUIT_INDICATOR;
69             //throw new IdentifierGenerationException("save associated object first, or disable cascade for inverse association");
70 }
71         return id;
72     }
73
74     /**
75      * @see org.hibernate.id.Configurable#configure(org.hibernate.type.Type, java.util.Properties, org.hibernate.dialect.Dialect)
76      */
77     public void configure(Type type, Properties JavaDoc params, Dialect d)
78         throws MappingException {
79
80         propertyName = params.getProperty("property");
81         entityName = params.getProperty(ENTITY_NAME);
82         if (propertyName==null) throw new MappingException(
83             "param named \"property\" is required for foreign id generation strategy"
84         );
85     }
86
87 }
88
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