Re: Change tracking API in Cayenne

I haven't worked with the GraphDiff API much, but it's not super easy to
turn a GraphDiff into something immediately useful.

When I've needed things like this I've usually constructed a
List<Map<String, Object>> with a row for each changed object and a map with
attribute/relationship key to the new value. Looking at
NodePropertyChangeOperation - it has the key and the old and new value, but
the API doesn't have any way of extracting that information that I see.

Most likely I just don't understand how to use this correctly, but I'm
guessing I wouldn't be the only one.

On Fri, Oct 11, 2019 at 5:36 AM Andrus Adamchik <[email protected]>
wrote:

> 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