Reverse Engineering dynamic-update="true"

wooglin280 · **Joined:** Mon Jun 02, 2008 4:20 pm **Posts:** 4

Hello,

I have been having trouble trying to get the Hibernate tools reverse engineering to generate my hbm.xml files with dynamic-update="true". I am trying to implement optimistic locking and according to the hibernate docs, dynamic-update has to be set to true. Can someone help me out here?

Here's my custom ReverseEngineeringStrategy.

Code:

package com.voyager.vpd.hibernate.reveng;


import java.util.List;

import org.apache.log4j.Logger;
import org.hibernate.cfg.reveng.DelegatingReverseEngineeringStrategy;
import org.hibernate.cfg.reveng.ReverseEngineeringStrategy;
import org.hibernate.cfg.reveng.TableIdentifier;

public class VPDReverseEngineeringStrategy extends DelegatingReverseEngineeringStrategy {
  private static Logger log = Logger.getLogger(VPDReverseEngineeringStrategy.class);
  private static final String COL_OPTIMISTIC_LOCK = "ModifiedDate";
  
  public VPDReverseEngineeringStrategy (ReverseEngineeringStrategy delegate) {
    super(delegate);
  }
  
  /**
   * Overrides the default generation strategy from assigned to native.
   */
  @Override
  public String getTableIdentifierStrategyName(TableIdentifier tableIdentifier) {
    String configuredName = super.getTableIdentifierStrategyName(tableIdentifier);
    if (configuredName == null) {
      configuredName = "native";
      log.debug("Used default strategy of " + configuredName);      
    }else {
      log.debug("Used configured strategy of " + configuredName);
    }
    return configuredName;
  }

  /**
   * Overrides the default collection name generation. 
   * Fixes generation of names like 'AccessKeyies', 'Surveyies', etc...
   */
  @Override
  public String foreignKeyToCollectionName(String keyname, TableIdentifier fromTable, List fromColumns,
      TableIdentifier referencedTable, List referencedColumns, boolean uniqueReference) {
    String collectionName = fromTable.getName();
    
    if (collectionName.matches(".*[a,e,i,o,u]y$")) {    
      collectionName += "s";
      log.debug("Set name configured as " + collectionName);
    }else {
      collectionName = super.foreignKeyToCollectionName(keyname, fromTable, fromColumns, referencedTable, referencedColumns, uniqueReference);
      log.debug("Set name configured as " + collectionName + "(hibernate tools default)");
    }
    
    return collectionName; 
  }
  
  @Override
  public boolean useColumnForOptimisticLock(TableIdentifier identifier, String column) {
    if (column.equals(COL_OPTIMISTIC_LOCK)) {
      log.debug("using " + column + " for optimistic locking");
      return true;
    }else {
      return false;
    }        
  }

  @Override
  public String getOptimisticLockColumnName(TableIdentifier identifier) {
    log.debug("called getOptimisticLockColumnName on table: " + identifier.getName());
        
    return COL_OPTIMISTIC_LOCK;
  }

}

Thanks

max · **Posted:** Tue Jun 03, 2008 3:46 am

I suggest you adjust your mapping files manually.

We don't support ever conceivable mapping via reverse engineering.

wooglin280 · **Joined:** Mon Jun 02, 2008 4:20 pm **Posts:** 4

Thanks for the reply. I will update my mapping files manually. However, i believe this to be a bug. If the wizard for Reverse Engineering has a check box to automatically detect optimistic locking it should also enable dynamic update, otherwise, optimistic locking is not truly enabled.

Any thoughts???

max · **Posted:** Thu Jun 05, 2008 8:04 am

huh ?

optimstic locking works perfectly fine without dynamic update.

When the docs say optimistic locking it is talking about <timestamp/> and/or <version/> not about field based optimstic locking.

wooglin280 · **Joined:** Mon Jun 02, 2008 4:20 pm **Posts:** 4

Here is an excerpt from the Hibernate Core documentation.

Quote:

If you enable dynamic-update, you will have a choice of optimistic locking strategies:
• version check the version/timestamp columns
• all check all columns
• dirty check the changed columns, allowing some concurrent updates
• none do not use optimistic locking
We very strongly recommend that you use version/timestamp columns for optimistic locking with Hibernate.
This is the optimal strategy with respect to performance and is the only strategy that correctly handles modifications
made to detached instances (ie. when Session.merge() is used).

I've also done some tests on my own to verify. The column i'm using for my <timestamp> is ModifiedDate.

If dynamic-update is not set to true the SQL generated is something like this:

Code:

UPDATE ... FROM ... WHERE id = ?

If dynamic-update is set to true the SQL generated is something like this:

Code:

UPDATE ... FROM ... WHERE id = ? and ModifiedDate = ?

Am i misunderstanding the documentation and/or what optimistic locking is all about? Can you explain?

Thanks

max · **Posted:** Thu Jun 05, 2008 5:57 pm

The docs you refer to is saying you get *all* of the options enabled if you do that.

dynamic-update is not a requirment for version/timpstamp columns.

Look in the unit tests for hibernate - there are tons of <version> tags where dynamic-update="false" or simply just not set.

wooglin280 · **Joined:** Mon Jun 02, 2008 4:20 pm **Posts:** 4

Thanks Max. After reviewing the hibernate unit tests and double checking my test with dynamic-update="true" or "false", it appears that it does add the and modifiedDate = ? in either case.