JSON output format

[musjj]

Bringing back this idea from an old issue: #64
I still think there's some value to a JSON output format, even when there's --format now.

For example, I wanted to have a conditional formatting:
If both the artist and title name is available, I want to display {{ artist }} - {{ title }}.
If only the title name is available, I want to display {{ title }}.
I tried playing around with the default function, but I don't think this is possible.

This can be potentially implemented as part of the format string, but I think it's easier to just have the tool output JSON. This will be very powerful, because once you have a JSON string, you can do any logic you want with it. Also, JSON is available everywhere these days, even in the shell with tools like jq.

[hseg]

(note conditional formatting is also requested in #296 - this is clearly a pain point)

[bbb651]

+1 I think it's a lot better to include a small dependency than to reinvent the wheel with formatting.

My use case is using playerctl from within eww, which accepts json.

I made a python script using dbus-python (P.S. is it a good idea to relay on the playerctld mrpis insterface?) as a workaround for now

#!/usr/bin/env python3

import dbus
import json

player = dbus.SessionBus().get_object('org.mpris.MediaPlayer2.playerctld', '/org/mpris/MediaPlayer2')
metadata = player.Get('org.mpris.MediaPlayer2.Player', 'Metadata', dbus_interface='org.freedesktop.DBus.Properties')
print(json.dumps(metadata))

[rice-cracker-dev]

+1