Fixed: Correctly add missing new artist when an album's artist changes in musicbrainz

Fixes LIDARR-H

src/Lidarr.Api.V1/Artist/ArtistController.cs

@@ -31,6 +31,7 @@ namespace Lidarr.Api.V1.Artist
                                 IHandle<AlbumEditedEvent>,
                                 IHandle<AlbumDeletedEvent>,
                                 IHandle<TrackFileDeletedEvent>,
+                                IHandle<ArtistAddedEvent>,
                                 IHandle<ArtistUpdatedEvent>,
                                 IHandle<ArtistEditedEvent>,
                                 IHandle<ArtistsDeletedEvent>,
@@ -284,6 +285,12 @@ namespace Lidarr.Api.V1.Artist
             BroadcastResourceChange(ModelAction.Updated, GetArtistResource(message.TrackFile.Artist.Value));
         }
 
+        [NonAction]
+        public void Handle(ArtistAddedEvent message)
+        {
+            BroadcastResourceChange(ModelAction.Updated, GetArtistResource(message.Artist));
+        }
+
         [NonAction]
         public void Handle(ArtistUpdatedEvent message)
         {

src/NzbDrone.Core/ArtistStats/ArtistStatisticsService.cs

@@ -15,12 +15,14 @@ namespace NzbDrone.Core.ArtistStats
     }
 
     public class ArtistStatisticsService : IArtistStatisticsService,
+        IHandle<ArtistAddedEvent>,
         IHandle<ArtistUpdatedEvent>,
         IHandle<ArtistsDeletedEvent>,
         IHandle<AlbumAddedEvent>,
         IHandle<AlbumDeletedEvent>,
         IHandle<AlbumImportedEvent>,
         IHandle<AlbumEditedEvent>,
+        IHandle<AlbumUpdatedEvent>,
         IHandle<TrackFileDeletedEvent>
     {
         private readonly IArtistStatisticsRepository _artistStatisticsRepository;
@@ -68,6 +70,13 @@ namespace NzbDrone.Core.ArtistStats
             return artistStatistics;
         }
 
+        [EventHandleOrder(EventHandleOrder.First)]
+        public void Handle(ArtistAddedEvent message)
+        {
+            _cache.Remove("AllArtists");
+            _cache.Remove(message.Artist.Id.ToString());
+        }
+
         [EventHandleOrder(EventHandleOrder.First)]
         public void Handle(ArtistUpdatedEvent message)
         {
@@ -114,6 +123,13 @@ namespace NzbDrone.Core.ArtistStats
             _cache.Remove(message.Album.ArtistId.ToString());
         }
 
+        [EventHandleOrder(EventHandleOrder.First)]
+        public void Handle(AlbumUpdatedEvent message)
+        {
+            _cache.Remove("AllArtists");
+            _cache.Remove(message.Album.ArtistId.ToString());
+        }
+
         [EventHandleOrder(EventHandleOrder.First)]
         public void Handle(TrackFileDeletedEvent message)
         {

src/NzbDrone.Core/Music/Services/RefreshAlbumService.cs

@@ -14,6 +14,7 @@ using NzbDrone.Core.Messaging.Events;
 using NzbDrone.Core.MetadataSource;
 using NzbDrone.Core.Music.Commands;
 using NzbDrone.Core.Music.Events;
+using NzbDrone.Core.RootFolders;
 
 namespace NzbDrone.Core.Music
 {
@@ -27,6 +28,7 @@ namespace NzbDrone.Core.Music
     {
         private readonly IAlbumService _albumService;
         private readonly IArtistService _artistService;
+        private readonly IRootFolderService _rootFolderService;
         private readonly IAddArtistService _addArtistService;
         private readonly IReleaseService _releaseService;
         private readonly IProvideAlbumInfo _albumInfo;
@@ -41,6 +43,7 @@ namespace NzbDrone.Core.Music
 
         public RefreshAlbumService(IAlbumService albumService,
                                    IArtistService artistService,
+                                   IRootFolderService rootFolderService,
                                    IAddArtistService addArtistService,
                                    IArtistMetadataService artistMetadataService,
                                    IReleaseService releaseService,
@@ -57,6 +60,7 @@ namespace NzbDrone.Core.Music
         {
             _albumService = albumService;
             _artistService = artistService;
+            _rootFolderService = rootFolderService;
             _addArtistService = addArtistService;
             _releaseService = releaseService;
             _albumInfo = albumInfo;
@@ -123,7 +127,7 @@ namespace NzbDrone.Core.Music
                     Metadata = remote.ArtistMetadata.Value,
                     MetadataProfileId = oldArtist.MetadataProfileId,
                     QualityProfileId = oldArtist.QualityProfileId,
-                    RootFolderPath = oldArtist.RootFolderPath,
+                    RootFolderPath = _rootFolderService.GetBestRootFolderPath(oldArtist.Path),
                     Monitored = oldArtist.Monitored,
                     Tags = oldArtist.Tags
                 };