Hi Andrew,
I did it like this in a DataDomainListener:
@PreUpdate( { CayenneDataObject.class } )
public void handleBeforeUpdateHook( CayenneDataObject object ) {
if( object instanceof BeforeSaveHook ) {
((BeforeSaveHook)object).beforeSaveAction();
}
}
and then have BeforeSaveHook be an interface, and then implementing
beforeSaveAction in the DataObject classes. To get the actual changes, I also
didn't find anything handy, and ended up doing it like this (in my custom
DataObject subclass):
public Map<String,ValueDifference<Object>> changedAttributes() {
Set<String> attributeKeys = new HashSet<>( attributeKeys() );
Map<String,Object> dataRow = oc().getObjectStore().getSnapshot(
getObjectId() );
if( dataRow == null ) { // newly inserted object
dataRow = new HashMap<>();
for( String key : attributeKeys ) {
dataRow.put( key, null );
}
}
Map<String,Object> committedValues = new HashMap<>();
Map<String,Object> uncommittedValues = new HashMap<>();
for( String key : dataRow.keySet() ) {
if( !attributeKeys.contains( key ) ) continue;
committedValues.put( key, dataRow.get( key ) );
Object uncommittedValue = readPropertyDirectly( key );
uncommittedValues.put( key, uncommittedValue );
}
MapDifference<String,Object> difference = Maps.difference(
committedValues, uncommittedValues );
Map<String,ValueDifference<Object>> entriesDiffering =
difference.entriesDiffering(); // assuming the all keys will always be
present in both
return entriesDiffering;
}
(where ValueDifference and MapDifference are Guava classes). Hope it helps,
perhaps someone else has a better solution.
Maik
> Am 22.01.2019 um 17:06 schrieb Andrew Willerding <[email protected]>:
>
> I can't seem to find documentation, or better yet some examples for 4.0 or
> 4.1 that explains how to check for either a single property change or how to
> get a list of the property changes in an onPreUpdate callback. Unless I'm
> missing something obvious (entirely likely ;-) ) the Lifecycle events
> documentation doesn't seem to mention any way to do this. Is this something
> that I need to manually track in the application?
>
> Also, what should I do if I want to reject the changes inside of an
> onPreUpdate callback? Do I need to do an explicit rollback or simply throw a
> CayenneRuntimeException of some sort? I'm guessing it's an explicit rollback.
>
> Thanks,
>
> Andrew
>
>
>
