In observeDeep, can I learn about what was deleted?

#1

Hello!

I’m trying to use observeDeep() to synchronize our view model with our yjs document.

In our document, we have a Y.Array of Y.Map. When a Y.Map is deleted from the Y.Array, I want to delete the corresponding objects in our view model.

I know I can use the event.changes.deleted to get a list of items deleted from the Y.Array, and that I can do a item.content.getContent() to get to the Y.Map instance that was removed.

My problem is, I want to be able to do a Y.Map.get(“_id”) field of the Y.Map so I can correlate it against our view model.

Unfortunately, since the Y.Map is no longer a member of the Y.Doc, I can’t read any of its fields.

Is there any work around to be able to identify which Y.Map was deleted?

Thank you!

Jeremy

#2

It looks like I can do something like the below, but seems a bit fragile?

Screenshot 2023-02-27 at 11.31.28 AM
Screenshot 2023-02-27 at 11.31.28 AM1092×596 59.1 KB

#3

If order doesn’t matter, you could model it as a Y.Map of Y.Map. Then you would have access to the deleted id through event.changes.keys.

It’s unfortunate that you have to do a workaround rather than the yarray observe just passing the deleted values.

#4

Thank you for replying!

In this case, order does matter, but your suggestion is great and one, and one that I’m using already in the case of Y.Maps of Y.Maps.

#5

I faced the same exact issue re. Y.Array of Y.Map and need to get YMap on delete. As @dmonad has pointed out no data is kept that enables this. An approach like yours does work, however as it is undocumented and unsupported it isn’t a route I want to take.

In then end I’m used pEvent inside the observerDeep() Y.Map event handler to wait for the Y.Array delete event and when pEvent() resolves I still have access to the Y.Map item. Problem solved.

pEvent() has been a life saver for me in async situations like this. HTH.

FYI This is in my new app Clibu Notes.

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