Hi Andrus,
I had a way to do this when I migrated from EOF to Cayenne and needed to keep
it. This is what I came up with at the time (uses Guava). It’s a method on my
own 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;
}
Not really pretty, but works and doesn’t require reflection.
Maik
> Am 11.10.2019 um 12:28 schrieb Andrus Adamchik <and...@objectstyle.org>:
>
> Was just answering Cayenne change tracking question on StackOverlow [1], and
> realized that the only user-friendly API that allows to check for individual
> changes is "cayenne-commitlog" that only works during commit. All the
> pre-commit APIs are internal and require lots of hoop jumping. I think we can
> address that on the cheap in 4.2 by defining a method like this in
> GraphManager.java:
>
> GraphDiff getChanges();
>
> We already have such method implemented in ObjectStore, so there's really no
> effort and an immediate benefit. Or take it a step further and additionally
> implement filtering changes per object:
>
> GraphDiff getChanges(Persistent)
>
> Thoughts?
>
> Andrus
>
> [1]
> https://stackoverflow.com/questions/58318730/what-is-the-current-best-method-of-getting-the-changes-to-an-object-hierarchy-in
