Feature: better handling when loading a playlist containing non-existent songs

[mpogue2]

BUG: when a playlist is loaded, and songs are not present, the numbering of the remaining songs gets messed up. In Gero's example, two item 19's and two item 20's should not have occurred. This should never happen and it is a bug (I'll open this separately).

In my testing, I don't see the numeric duplication that Gero sees. However, I do see a GAP where the incorrect song used to be.

I guess there are a couple ways to handle this:

1. close the gap -- ensure that the numbering is always 1-N, where N = number of playable songs in the playlist (i.e. IGNORE songs that are not found). Feature: Put up a dialog instead of using the status bar, to list all errors at once.
2. show the gap -- still show the song that doesn't exist, but indicate that it is otherwise NOT playable, say with strikethrough or grey it out. At load time, either a) try to find the song (again), and if it's there, remove the strikethrough and load it as normal, or b) do not allow loading at all until the user fixes the problem and reloads the playlist.

In any case, when an error is seen by the user today, they can fix it (if it's iCloud/Dropbox/Box.net, they can click to ask the OS to download the file to make it local), and then reload the playlist, which should then correctly load. (I'm not aware of a way that Qt can itself do this.)

[Gero5]

I would prefer No. 2. mark the songs that are not playable. Because I really want to have the song in my playlist that is why I put it there. If I know that there is a problem with loading a song I can fix it. Usually I check the playlist at home before I move to the dance. If I do not see the missing songs and I find my playlist shortened by two or even more entries on the club night it causes unnecessary trouble.

[mpogue2]

I think that option # 2 makes sense. I'm gonna change this to a Feature rather than a Bug, and change the title accordingly.

[mpogue2]

OK, implementation notes:

• This is probably a change to MainWindow::loadPlaylistFromFile(), which for each playlist item scans through the songTable looking for matches (on the relative pathname). When one is found, that row's number field, pitch field, and tempo field are changed to that of the playlist row.
• For this change, if there is NO match found in the songTable, we'll need to ADD a new "non-playable" item to the songTable. Title in Red Strikethrough perhaps. Hovertext explaining the problem?
• The automatic post-load sorting by the "#" column will bring the "non-playable" row up to be visible to the user.
• When the user attempts to load a non-playable song (either via ENTER or double-click), perhaps an error dialog pops up at that point, with just an "OK" button.
• After the user fixes the error (if they choose to do so, either by telling the Cloud Storage provider to make the file local OR by manually modifying the CSV playlist file), they will need to reload the playlist, which will check everything for errors again. This should catch any renaming problems that the user introduced since the original load (e.g. A and B were on the playlist, but only A exists. B creates an error. User renames A to B -- we should reload the entire playlist at this point just to double check that everything exists. The playlist csv filename will be in the MRU list, so they just have to do Playlist > Load Recent Playlist > (first item on the list, most likely).
• I think this is 99.9% as good as using a FileWatcher, which is probably overkill for this problem. The FileWatcher could run automatically (although I'm not at all sure that it will catch the wacky things that the cloud storage providers do, like make shadow local versions of a file that was pushed to the Cloud, or making a cloud-only file now available locally), and it would catch other user-created errors, like manually renaming a playlist that was in the MRU list, but this situation is probably pretty rare.

[mpogue2]

Option 3: might be to pop up a dialog box, with a way to correct each entry that is wrong (e.g. modify or delete).

[mpogue2]

This will be addressed as part of the new DarkMode prototype in #921. See this comment.

Basically, invalid items will be highlighted at Load Playlist time, and the user will be able to manually edit the playlist with a text editor, and reload the playlist to ensure that the edits fixed the problem.

@Gero5 To address the "Dropbox/Box.net/iCloud moved my file to the Cloud" use case, we might also need a context menu option on each missing item, something like "Open containing folder", so that the user can click on the little cloud icon to re-download the missing file. In this case, it's not an error in the playlist.csv file, it's that the file is only in the Cloud.

[mpogue2]

OK, I thought about it, and went ahead and implemented it: 26da7040821f9404e5dd1b15050ac3ff18f4513d

Added a new context menu for playlist entries:

• If the file exists, "Show In Enclosing Folder" will open the folder containing the file in Finder, and the file will be highlighted.
• If the file does NOT exist, "Show Enclosing Folder" (note subtle change of wording) will open the folder where the file was SUPPOSED to be (but isn't), using the Finder. Alternate too-long name: "Show the Folder where the file was supposed to be"

So, if a playlist file was moved or deleted, it will be a 3-step process to fix it:

• RIGHT-CLICK on the red highlighted missing filename > Show Enclosed Folder, look for the renamed file there (or find it elsewhere using the Finder)
• RIGHT-CLICK on the playlist header > Edit '' in Text Editor, fix the file pathname (or delete the line, if the file is no longer wanted), and File > Save.
• RIGHT-CLICK on the playlist header > Reload '<playlistname'

[mpogue2]

I think this is implemented now, so closing.