PkGenerator


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19  
20  
21  package org.apache.cayenne.dba;
22  
23  import java.util.List  ;
24  
25  import org.apache.cayenne.access.DataNode;
26  import org.apache.cayenne.map.DbEntity;
27  
28  /**
29   * Defines methods to support automatic primary key generation.
30   * 
31   * @author Andrus Adamchik
32   */
33  public interface PkGenerator {
34  
35      /**
36       * Generates necessary database objects to provide automatic primary key support.
37       * 
38       * @param node node that provides access to a DataSource.
39       * @param dbEntities a list of entities that require primary key autogeneration
40       *            support
41       */
42      void createAutoPk(DataNode node, List   dbEntities) throws Exception  ;
43  
44      /**
45       * Returns a list of SQL strings needed to generates database objects to provide
46       * automatic primary support for the list of entities. No actual database operations
47       * are performed.
48       */
49      List   createAutoPkStatements(List   dbEntities);
50  
51      /**
52       * Drops any common database objects associated with automatic primary key generation
53       * process. This may be lookup tables, special stored procedures or sequences.
54       * 
55       * @param node node that provides access to a DataSource.
56       * @param dbEntities a list of entities whose primary key autogeneration support
57       *            should be dropped.
58       */
59      void dropAutoPk(DataNode node, List   dbEntities) throws Exception  ;
60  
61      /**
62       * Returns SQL string needed to drop database objects associated with automatic
63       * primary key generation. No actual database operations are performed.
64       */
65      List   dropAutoPkStatements(List   dbEntities);
66  
67      /**
68       * Generates new (unique and non-repeating) primary key for specified DbEntity.
69       * 
70       * @param ent DbEntity for which automatic PK is generated.
71       */
72      Object   generatePkForDbEntity(DataNode dataNode, DbEntity ent) throws Exception  ;
73  
74      /**
75       * Resets any cached primary keys forcing generator to go to the database next time id
76       * generation is requested. May not be applicable for all generator implementations.
77       */
78      void reset();
79  }
80
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