[CAY-584] Add method to check if a property has changed

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: Undefined future
• Fix Version/s: Undefined future
• Component/s: Core Library
• Assignee: Unassigned
• Reporter: Øyvind Harboe
• Created: 01/Jul/06 10:55
• Updated: 01/Jun/11 15:29

Description

Here is the code. I've tested isChanged() and it appears robust for both normal properties and foreign key relationships.

package org.objectstyle.cayenne.access;

import org.objectstyle.cayenne.DataObject;
import org.objectstyle.cayenne.ObjectId;

public class CayenneUtils
{
/** this version of isChanged can only be used for foreign key relationship properties */
private static boolean isChangedArc(DataObject o, String propName)
{
ObjectDiff diff = (ObjectDiff) o.getDataContext().getObjectStore().getChangesByObjectId().get(o.getObjectId());
Object oldValue = diff.getArcSnapshotValue(propName);
ObjectId newId=((DataObject) o.readProperty(propName)).getObjectId();
/* ick! old or new value can be null which .equals() does not support */
if (newId==oldValue)

{ return false; } else if ((newId==null) || (oldValue==null))
{ return true; } else
{ return !oldValue.equals(newId); }
}

/**
* this version of isChanged can only be used for normal properties and not
* relationships.
*/
private static boolean isChangedProperty(DataObject o, String propName)
{
ObjectDiff diff = (ObjectDiff) o.getDataContext().getObjectStore().getChangesByObjectId().get(o.getObjectId());
Object oldValue = diff.getSnapshotValue(propName);
Object newValue= o.readProperty(propName);
if (newValue==oldValue)
{ return false; }

else if ((newValue==null) || (oldValue==null))

{ return true; }

else

{ return !oldValue.equals(newValue); }

}

/** checks if a property or foreign key relationship changed */
public static boolean isChanged(DataObject o, String propName)
{
ObjectDiff diff = (ObjectDiff) o.getDataContext().getObjectStore().getChangesByObjectId().get(o.getObjectId());
if (diff.containsArcSnapshot(propName))

{ return isChangedArc(o, propName); }

else

{ return isChangedProperty(o, propName); }

}
}