Support syncing macOS Finder file tags

[alexhaas]

As far as I can tell, Nextcloud does not support syncing tags that are added to files in Finder on macOS (https://support.apple.com/en-us/HT202754). Since Dropbox supports syncing these tags, I think it would be extremely beneficial to add this to the Nextcloud feature set.

Steps to reproduce

1. Install Nextcloud on more than one Mac.
2. Add a tag to a synced file.
3. Tag never syncs to other computers.

Expected behaviour

The tags should be synced (like Dropbox).

Actual behaviour

Nothing happens.

[crobarcro]

One method of implementing local tagging would be to use a hidden folder in the nextcloud top level directory, e.g. .nextcloud/tags where tags for all the user's files are synced. Then use this in some interface to add or view the tags. This would then be cross-platform.

An open source program which takes the local database approach is TMSU (GPLv3):

https://github.com/oniony/TMSU

Ideally to add tags on the various operating systems there would be a right-click menu option in the file browser to add tags, or view tags for the file. The biggest issue would be Linux users because of the fragmented desktop experience (but we are more willing to set up such things ourselves).

Qt has a completer widget which could be useful for setting the tags:

http://doc.qt.io/qt-5/qtwidgets-tools-customcompleter-example.html

This could be completely separate from the desktop client, so would not require diverging from the owncloud client. It would only require that the tags folder for each user is automatically updated when anyone adds a tag, so a server thing.

[MorrisJobke]

Duplicate of #206

[alexhaas]

I feel like #206 isn’t quite the same issue as this. File tags already exist on macOS and if you use them with Nextcloud, they are not synced. Dropbox syncs these quite well.

[jospoortvliet]

If we'd add tags, we would support our own tags - Nextcloud tags, I mean. Doing something JUST for one operating system, that doesn't work on others, is pretty useless to 99% of our users. It's a legitimate request and indeed different from #206 in some way but it is not something we want to do.

However, it might be possible to sync the tags in Mac OS with Nextcloud, and I'm sure we'll try to do that in #206 if it is feasible.

[helmut72]

@jospoortvliet: great 👍

Btw, it's not only macOS but also iOS, if Nextcloud on iOS supports tags anytime 😉

[alexhaas]

Thanks for the reply. This isn’t just about supporting, or special-casing one system, like macOS. Nextcloud ignores all extended file attributes during sync, which is causing data loss.

http://en.wikipedia.org/wiki/Extended_file_attributes