improve UX when encountering missing/invalid library directory

[mixxxbot]

Reported by: ronso0
Date: 2021-07-23T16:45:10Z
Status: New
Importance: Undecided
Launchpad Issue: lp1937851
Tags: library, usability

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Amongst others, my library contains a folder on an external drive.
That drive was not mounted when I wanted to add a subfolder of my home directory. Adding was refused, message says it's already in the library or the library is being scanned. Neither was true.
That was driving me crazy so I removed all watched folders to finally figur it's failing due to the unmounted drive :\

the message

mixxx/src/library/library.cpp

Lines 504 to 509 in 3546054

	if (!m_pTrackCollectionManager->addDirectory(mixxx::FileInfo(dir))) {
	QMessageBox::information(nullptr,
	tr("Add Directory to Library"),
	tr("Could not add the directory to your library. Either this "
	"directory is already in your library or you are currently "
	"rescanning your library."));

caused by

mixxx/src/library/dao/directorydao.cpp

Line 68 in 3546054

if (!oldDir.exists() || !oldDir.isDir()) {

Though the logged line is clear about the cause:

Aborting to add QFileInfo(/home/abc/Music/mmumu) : Loaded directory QFileInfo(/mnt/yxo/audio) does not exist or is inaccessible

After closing the dialog and hitting Apply in the preferences Mixxx says "one or more directories were added... Rescan / Cancel"
Also wrong.

1. can DirectoryDAO::AddResult be passed through to the requester so that we can have explicit error messages?

2. Why is a missing directory hindering the addition of others in the first place? I'm aware the dir is missing, that was the reason to add another track source ;)

[mixxxbot]

Commented by: ronso0
Date: 2021-07-23T17:35:37Z

---

only affects main/2.4, 2.3 does handle this case satisfactory.

[mixxxbot]

Commented by: ronso0
Date: 2021-07-23T17:37:51Z

---

Re 1) pass DirectoryDAO::AddResult through to the requester
Is there a smarter way than adding identical enums to trackcollection and trackcollectionmanager?

[ronso0]

IMO it's a valid use case to have a thumb drive added (temporarily) and not having that attached/mounted when adding another directory.

First setp is to show the actual reason for failure in the error message.

Next, someone could explain to me why we can't add new directories when one listed directory is missing?
Or how we could deal with this instead of rejecting new directories altogether?

[daschuer]

No one is working on it. So let's removevthd milestone.