private async Task <bool> UpdatePlaylistSongs(string[] selectedSongs, PlaylistModel playlistModel)
{
try
{
//Gets connections from the db including the playlists and the songs inside.
var connections = await _context.PlaylistSongsConnections
.Include(connection => connection.Playlist).Include(connection => connection.Song).ToListAsync();
//Getting all connections of the given playlist.
var playlistSongs = (from connection in connections
where connection.Playlist != null && connection.Playlist.ID == playlistModel.ID
select connection.Song.ID).ToList();
// For performance we use HashSet of the selected songs from the edit view of the playlist
var selectedSongsHS = new HashSet <string>(selectedSongs);
// Iterate all songs in the DB
foreach (var song in _context.Songs)
{
// Check if the current song from DB is selected by the view
if (selectedSongsHS.Contains(song.ID.ToString()))
{
// Assign the song to the playlist, if the playlist isn't assigned yet
if (!playlistSongs.Contains(song.ID))
{
var connection = new PlaylistSongModel()
{
Playlist = playlistModel,
Song = song
};
_context.PlaylistSongsConnections.Add(connection);
}
}
else
{
// If we are here than the song is not selected, and if the playlist currently assigned to this song
// we should than unassign the playlist and update the song DB
if (playlistSongs.Contains(song.ID))
{
var connectionToDelete = connections.FirstOrDefault(connection => connection.Song.ID == song.ID);
_context.PlaylistSongsConnections.Remove(connectionToDelete);
}
}
}
}
catch (Exception)
{
return(false);
}
return(true);
}
private async Task <bool> CreatingPlaylistConnections(string[] selectedSongs, PlaylistModel playlist)
{
try
{
// For performance we use HashSet of the selected songs from the edit view of the playlist.
var selectedSongsHS = new HashSet <string>(selectedSongs);
var songsConnections = new List <PlaylistSongModel>();
// The current songs of the playlist.
// var playlistSongs = new HashSet<int>(playlist.Playlist.Select(s => s.ID));
// Iterate all songs in the DB.
foreach (var song in _context.Songs)
{
// Check if the current song from DB is selected by the view.
if (selectedSongsHS.Contains(song.ID.ToString()))
{
//Creating a connection.
var connection = new PlaylistSongModel()
{
Playlist = playlist,
Song = song
};
//Add it to the local list.
songsConnections.Add(connection);
}
}
//Saving the new collection in the db.
await _context.PlaylistSongsConnections.AddRangeAsync(songsConnections);
await _context.SaveChangesAsync();
}
catch (Exception)
{
return(false);
}
return(true);
}
