Reverting a ChangeSet

[kinglozzer]

Are there any plans to implement this feature (issues like silverstripe/silverstripe-campaign-admin#43 suggest there might be, even if not immediate)? I’m stuck half-way down the rabbit hole at the moment, and I don’t want to duplicate efforts!

I’ve done a minimal amount of work to get ChangeSetItem::revert() functional, but it’s nowhere near PR ready at the moment: kinglozzer@6a762b1. So far, I’ve been working towards what’s documented in the original RFC, but I suspect that a few practicalities may change things there (e.g. is the ability to “revert a revert” feasible?). Things I’m currently stuck on/intimidated by:

• Publishing a ChangeSet invokes RecursivePublishable::unlinkDisownedObjects(). Does this need to (somehow) be undone during a revert? Is it even possible to revert that?
• ChangeSet::isSynced() returns false when attempting to revert a ChangeSet that includes an item that was added implicitly. My guess is that this is because ChangeSetItem::findReferenced() doesn’t take into account the current state of the ChangeSet (open vs published), but I’ve not actually looked into this yet

I’m happy to open a PR if that’d be a more appropriate place to discuss this, I just didn’t want to open a *** DO NOT MERGE *** one 😉

[chillu]

FYI I've created a similar issue for rolling back a particular owner incl. all of its owned relationships. That can be different from a changeset, since a changeset can contain multiple owners: #94