Fixed: Multiple artists found during manual import prevents manual importing from folder

(cherry picked from commit 00c922875f7a41c9e1750e0257764bd633f41746)

Fix

src/NzbDrone.Core.Test/MusicTests/ArtistRepositoryTests/ArtistRepositoryFixture.cs

@@ -135,8 +135,8 @@ public void should_not_find_artist_if_multiple_artists_have_same_name()
 
             _artistRepo.All().Should().HaveCount(4);
 
-            var artist = _artistRepo.FindByName(Parser.Parser.CleanArtistName(name));
+            Action act = () => _artistRepo.FindByName(Parser.Parser.CleanArtistName(name));
-            artist.Should().BeNull();
+            act.Should().Throw<MultipleArtistsFoundException>();
         }
 
         [Test]

src/NzbDrone.Core/MediaFiles/TrackImport/Manual/ManualImportService.cs

@@ -153,7 +153,15 @@ private List<ManualImportItem> ProcessFolder(string folder, string downloadId, A
         {
             DownloadClientItem downloadClientItem = null;
             var directoryInfo = new DirectoryInfo(folder);
-            artist = artist ?? _parsingService.GetArtist(directoryInfo.Name);
+
+            try
+            {
+                artist ??= _parsingService.GetArtist(directoryInfo.Name);
+            }
+            catch (MultipleArtistsFoundException e)
+            {
+                _logger.Warn(e, "Unable to find artist from title");
+            }
 
             if (downloadId.IsNotNullOrWhiteSpace())
             {

src/NzbDrone.Core/Music/MultipleArtistsFoundException.cs

@@ -0,0 +1,27 @@
+using NzbDrone.Common.Exceptions;
+
+namespace NzbDrone.Core.Music
+{
+    public class MultipleArtistsFoundException : NzbDroneException
+    {
+        public MultipleArtistsFoundException(string message, params object[] args)
+            : base(message, args)
+        {
+        }
+
+        public MultipleArtistsFoundException(string message)
+            : base(message)
+        {
+        }
+
+        public MultipleArtistsFoundException(string message, System.Exception innerException)
+            : base(message, innerException)
+        {
+        }
+
+        protected MultipleArtistsFoundException(string message, System.Exception innerException, params object[] args)
+            : base(message, innerException, args)
+        {
+        }
+    }
+}

src/NzbDrone.Core/Music/Repositories/ArtistRepository.cs

@@ -61,7 +61,9 @@ public Artist FindByName(string cleanName)
         {
             cleanName = cleanName.ToLowerInvariant();
 
-            return Query(s => s.CleanName == cleanName).ExclusiveOrDefault();
+            var artists = Query(s => s.CleanName == cleanName).ToList();
+
+            return ReturnSingleArtistOrThrow(artists);
         }
 
         public Artist GetArtistByMetadataId(int artistMetadataId)
@@ -91,5 +93,20 @@ public List<Artist> GetArtistByMetadataId(IEnumerable<int> artistMetadataIds)
         {
             return Query(s => artistMetadataIds.Contains(s.ArtistMetadataId));
         }
+
+        private static Artist ReturnSingleArtistOrThrow(List<Artist> artists)
+        {
+            if (artists.Count == 0)
+            {
+                return null;
+            }
+
+            if (artists.Count == 1)
+            {
+                return artists[0];
+            }
+
+            throw new MultipleArtistsFoundException("Expected one artist, but found {0}. Matching artists: {1}", artists.Count, string.Join(",", artists.Select(s => s.Name)));
+        }
     }
 }