Playlist allows multiple entries of the same event

[dennis531]

The implemented playlists API allows to add an event multiple times to a playlist. In the Stud.IP Opencast Plugin, multiple occurrences are not yet supported in the existing playlists. I think we should find a common solution to avoid incompatibilities between systems like Stud.IP and Tobira. So we should not allow multiple occurrences if we really do not need them. If I see correctly, youtube videos can only be added to a playlist once. If we have no restriction, users might lose track of large playlists and unintentionally add a video to a playlist multiple times.

In general, we should consider whether there are any use cases.

[LukasKalbertodt]

👍 for specifying that clearly!

Thinking about use cases for having a video in a playlist multiple times:

• A educational playlist with individual lessons, where in between some lessons a user wants to add a short utility video (e.g. saying "Now please pause this playlist and look at your exercise sheets").
• Similarly, say someone creates a home workout playlist out of individual exercises, but they of course want to repeat some exercises.
• Playlist of songs where someone wants to play some songs multiple times.

From these, the "home workout" one seems most convincing to me, the others are rather far fetched I feel. Your point of getting an error/warning when adding a video to a playlist twice is good I think: certainly with song playlists, I usually don't want to add a song multiple times, and was happy about my music service telling me "the song is already in the playlist". That service gave me the option to add it anyway though!

So I think I'm slightly leaning to "allow multiple times in playlist", because:

• The useful error (only advantage of the restriction that I see) can also be implemented as warning while still allowing users to add it if they really want.
• Allows us to cover the "home workout" case as well as other use cases that we haven't thought of yet.
• Would not require any changes in OC anymore.

[dennis531]

In our internal discussion, we came to the conclusion that we don't have any specific use case in Stud.IP for multiple entries of the same video. Therefore, we would not provide this function for users, but the restrictions in the database should still be removed and the display should be possible.

Related issue: elan-ev/studip-opencast-plugin#965.