Songs with no artists cause pyportify to stop working.

Hi rckclmbr, I'm trying to use pyportify to copy my music to GPM. I found pyportify but when I try and use it on my main playlist (https://open.spotify.com/user/1112911680/playlist/4Uqi6PgbGU69RkzGLcYtQM) this is the error I get:

Gathering tracks for playlist Good Music (387)
Not emitting portify
Not emitting portify
Traceback (most recent call last):
  File "/usr/local/bin/pyportify-copyall", line 11, in <module>
    sys.exit(main())
  File "/usr/local/lib/python3.5/dist-packages/pyportify/copy_all.py", line 61, in main
    loop.run_until_complete(start())
  File "/usr/lib/python3.5/asyncio/base_events.py", line 337, in run_until_complete
    return future.result()
  File "/usr/lib/python3.5/asyncio/futures.py", line 274, in result
    raise self._exception
  File "/usr/lib/python3.5/asyncio/tasks.py", line 239, in _step
    result = coro.send(None)
  File "/usr/local/lib/python3.5/dist-packages/pyportify/copy_all.py", line 55, in start
    yield from app.transfer_playlists(None, session, s, g, playlists)
  File "/usr/local/lib/python3.5/dist-packages/pyportify/app.py", line 195, in transfer_playlists
    queries = get_queries(d_list['uri'], sp_playlist_tracks)
  File "/usr/local/lib/python3.5/dist-packages/pyportify/spotify.py", line 9, in get_queries
    if "artists" in sp_track:
TypeError: argument of type 'NoneType' is not iterable

Thanks, Snowl

Trying to migrate a lot of playlists and I was seeing this on a few, breaking the whole process part way through. I did a little investigation.

The initial exception was raised from spotify.py, lin 14:

        if "artists" in self.sp_track['track']:

...where self.sp_track['track'] is None.

This SpotifyQuery object is created from app.py, line 159:

query = SpotifyQuery(i, sp_playlist_uri, sp_track, track_count)

...where sp_track['track'] is None.

Since sp_track at this point comes from enumerate(sp_playlist_tracks), I added a little check in here to dump the data:

            if sp_track['track'] is None:
                raise Exception("None track in playlist:\n{0}".format(sp_playlist_tracks))

That data contains a track like this:

[
...
  {
    'added_by': None,
    'track': None,
    'is_local': None,
    'added_at': None
  },
...
]

I wondered if this was a completely fake track inserted in here, or a track that exists that we're missing the data for. So I checked:

The track before and after that one are adjacent tracks in the playlist this represents, when I view it in Spotify.
There are tracks now unavailable in this playlist, but this isn't at the position of one of them, and those ones are coming through fine.
The dumped data shows 52 tracks with real info, and this one. The playlist in Spotify, including now-unavailable tracks (greyed-out), has only 52 items.

So this just appears to just be a weird fake item inserted in between, and I figure I can safely ignore it. I've ended up skipping these by adding this at app.py, line 159:

            if sp_track['track'] is not None:

... and indenting the following 3 lines of course to nest them in that check.

This resolves the issue for me. If I get a little more time later I will submit a patch for it.

rckclmbr / pyportify

Songs with no artists cause pyportify to stop working. #64