Adding multiple tracks to a playlist in a single request doesn't work

[itsaphel]

These took a while to debug and identify the issues themselves. Apologies if this report lacks helpful information to resolve the issue - it's 4AM now and I need to catch some sleep so I haven't really had time to figure out why the second issue is occurring.

---

First issue: The example and test is wrong I believe, perhaps a recent update broke this: https://github.com/thelinmichael/spotify-web-api-java/blob/master/examples/data/playlists/AddTracksToPlaylistExample.java

This track ID alone won't work. A full Spotify URI has to be entered as a value.

---

Second issue: Adding more than one track per request (AddTracksToPlaylist request) bugs out. I haven't had a chance to check why exactly, but the SnapshotResult object that it returns is null with no exceptions printed. Tracks are not added to the playlist. Making one request per track, however, works.

According to the Spotify API docs up to 100 tracks per request should be possible to be added. I'm guessing they made an API change and the library's method of adding tracks to the request is outdated.

[itsaphel]

A quick guess just looking at their doc, perhaps wrong:

A valid request with multiple tracks, from their docs:
curl -i -X POST "https://api.spotify.com/v1/users/wizzler/playlists/7oi0w0SLbJ4YyjrOxhZbUv/tracks?uris=spotify%3Atrack%3A4iV5W9uYEdYUVa79Axb7Rh,spotify%3Atrack%3A1301WleyT98MSxVHPZCA6M" -H "Authorization: Bearer {your access token}" -H "Accept: application/json"

This library encodes the colon into %3A correctly, but also encodes the commas from looking at my debugger earlier today. That might be the issue, and Spotify might treat it as one long track URI that is invalid.

Just a guess, perhaps a wrong one but might be helpful if it's on the right lines. I'll take a closer look tomorrow if I get a chance.

[dargmuesli]

Thanks for the catch, I've updated the example and the unit test. I could not reproduce your second issue though. I'll wait a few days before I release version 2.0.4 so that you can give me more information on this issue.

[itsaphel]

Hey,

Been away all week. I'll get my code pushed to GitHub today and give some more information.

[itsaphel]

Take a look here: https://github.com/itsaphel/tv-playlist-generator-cli/blob/master/src/main/java/io/indices/tvplaylistgenerator/streaming/Spotify.java#L105-L130

Sending more than 1 track per request causes some form of error. An exception is not thrown or printed, but the addTracksToPlaylistRequest var is null and the request isn't successful.

[dargmuesli]

Still works for me, even in your project (PR).

[itsaphel]

@dargmuesli Still having some troubles with this.

Your PR: itsaphel/tv-playlist-generator-cli#2

Testing on a show with 277 songs (id is "power"). I think your batch code causes some number issues (e.g. on second run, i = 100, subList toIndex = (277 - 100 * 100) = -9000 something.

I replaced with the following batching code: https://github.com/itsaphel/tv-playlist-generator-cli/blob/master/src/main/java/io/indices/tvplaylistgenerator/streaming/Spotify.java#L112-L119

On the first run it has batch fromIndex = 0, toIndex = 99. (I tried 99 batch size because 100 didn't work). snapshotResult is null on this run. Any ideas? Still seems to me like it could be a bug with the library?

You should be able to reproduce with a large show (I used show ID "power"). To run the app you pretty much just need to fill in a clientId, clientSecret and appUrl in a config.json. The authentication code is manually pasted into the CLI.

[dargmuesli]

Hmm, dunno what I confused there 3 years ago, but this line should work better
List<String> subList = trackIds.subList(i, i + 100 - 1);
The for loop goes in steps 0, 100, 200 and now the first sublist uses indices 0 to 0 + 100 - 1 = 99, then 100 to 100 + 100 - 1 = 199 and so on.