Incompabilities with MPD protocol v0.19

[kingosticks]

It looks like we missed a few changes in version 0.19 of the MPD protocol in mopidy/mopidy#1213. Below is the entire list of protocol changes taken from MPD's 0.19 (2014/10/10) changelog:

• new commands "addtagid", "cleartagid", "listfiles", "listmounts", "listneighbors", "mount", "rangeid", "unmount"
• "lsinfo" and "readcomments" allowed for remote files
• "listneighbors" lists file servers on the local network
• "playlistadd" supports file:///
• "idle" with unrecognized event name fails
• "list" on album artist falls back to the artist tag
• "list" and "count" allow grouping
• new "search"/"find" filter "modified-since"
• "seek*" allows fractional position
• close connection after syntax error

The new grouping functionality for list is being used by MPDroid and was originally reported in https://github.com/mopidy/mopidy/issues/1314.

• sticker database

[kingosticks]

We also have an outstanding TODO for readcomments to add some tests before not implementing but I don't think the MPD protocol change to allow usage with remote files really applies to us here.

[adamcik]

We could also consider making the version we report a config option. That way you could downgrade if you run into issues without code changes. Of course this might just be confusing for end users.

[ghost]

We could also consider making the version we report a config option

Wouldn't that need additional code? I mean, supporting multiple versions of a protocoll usually is complicated, too.

Anyway, I would love to see this issue fixed because it seems to make MPDroid (MPD client for Android) unusable with Mopidy, see https://github.com/mopidy/mopidy/issues/1314 and mopidy/mopidy#1246.

[kingosticks]

It'd need a small amount of code now to implement such a config option but I think the point is that it'd save end users having to hack the protocol version as they may currently do.

Implementing the real fix is a bit tricky in some places and considerably more work. I had a branch implementing 'group by' but I ended up needing to change Mopidy's core API and then consequently needed to patch some of the backend extensions. Perhaps there's a simple way to avoid all that if someone has the motivation to get into it.

[kingosticks]

As well as GROUP BY support, we should try and get all of these into v3.0. My hacked branch for grouping support is at https://github.com/kingosticks/mopidy/tree/mpd/group_by

[JerwuQu]

Shouldn't stickers also be a part of this?

For me, it's very essential for organizing my music.

[kingosticks]

Yes, ideally, but AFAIK it's not a widely used feature so we'll definitely need someone to take that on. I think it was implemented back in v0.15!