FAQ

On Sat, Mar 12, 2011 at 3:43 AM, Andrus Adamchik wrote:
Yeah, I totally understand how this can be useful. I am trying to analyze the situation and just like with most things in Cayenne core it can get pretty deep.
Yeah, whenever I go into the stack it takes me a while to remember things.
Some factors to consider:

1. Performance (I mentioned about that before).
I completely understand this.
2. "Circular changes" canceling modifications:

assertEquals("A", o.getP());
o.setP("B"); // modified
o.setP("A"); // modified? (property change is "canceled", but maybe other properties are also modified)
I'd be OK with a circular change showing up as modified. They made a
change. Then they made another change. I'm OK with that. (I'm
thinking of data entry in the UI here.)
3. "Uncommittable changes". An example - objects with modified to-many relationships are treated as modified, but during commit their DB records are not updated.
I'm not sure this is a big issue. The object graph has indeed been
modified in this case. Yes, it would be more ideal if the parent of
the to-many didn't show up when you called modifiedObjects(), but for
the boolean hasChanges(), it would work out fine.
So I am leaning towards either a method like ObjectContext.hasCommittabledChanges() that would do deeper analysis of the object graph, or maybe a more involved changeset API that I started to draft under cayenne-lifecycle, that would among other things allow the caller to obtain a more nuanced and detailed view of the graph changes (overall changes, changes per object, committable/uncommitable changes etc.)
Would hasCommittableChanges() really add any other value over
hasChanges() if hasChanges() was "fixed"? Or perhaps you are worried
about backward compatibility of the API?
And there's of course we shouldn't forget ROP....
Sadly, I often do. :-(
Andrus
mrg

PS. Would has*Changes() fix Embeddables, too? (Although I'm actually
trying to get rid of the ones in the current project.)

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postedMar 11, '11 at 8:23p
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