Fixed: Improve validation for individual album adding

src/Lidarr.Api.V1/Albums/AlbumController.cs

@@ -42,6 +42,14 @@ namespace Lidarr.Api.V1.Albums
                            IMapCoversToLocal coverMapper,
                            IUpgradableSpecification upgradableSpecification,
                            IBroadcastSignalRMessage signalRBroadcaster,
+                           RootFolderValidator rootFolderValidator,
+                           MappedNetworkDriveValidator mappedNetworkDriveValidator,
+                           ArtistPathValidator artistPathValidator,
+                           ArtistAncestorValidator artistAncestorValidator,
+                           RecycleBinValidator recycleBinValidator,
+                           SystemFolderValidator systemFolderValidator,
+                           AlbumExistsValidator albumExistsValidator,
+                           RootFolderExistsValidator rootFolderExistsValidator,
                            QualityProfileExistsValidator qualityProfileExistsValidator,
                            MetadataProfileExistsValidator metadataProfileExistsValidator)
 
@@ -51,11 +59,34 @@ namespace Lidarr.Api.V1.Albums
             _releaseService = releaseService;
             _addAlbumService = addAlbumService;
 
-            PostValidator.RuleFor(s => s.ForeignAlbumId).NotEmpty();
-            PostValidator.RuleFor(s => s.Artist.QualityProfileId).SetValidator(qualityProfileExistsValidator);
-            PostValidator.RuleFor(s => s.Artist.MetadataProfileId).SetValidator(metadataProfileExistsValidator);
-            PostValidator.RuleFor(s => s.Artist.RootFolderPath).IsValidPath().When(s => s.Artist.Path.IsNullOrWhiteSpace());
-            PostValidator.RuleFor(s => s.Artist.ForeignArtistId).NotEmpty();
+            PostValidator.RuleFor(s => s.ForeignAlbumId).NotEmpty().SetValidator(albumExistsValidator);
+            PostValidator.RuleFor(s => s.Artist).NotNull();
+            PostValidator.RuleFor(s => s.Artist.ForeignArtistId).NotEmpty().When(s => s.Artist != null);
+
+            PostValidator.RuleFor(s => s.Artist.QualityProfileId).Cascade(CascadeMode.Stop)
+                .ValidId()
+                .SetValidator(qualityProfileExistsValidator)
+                .When(s => s.Artist != null);
+
+            PostValidator.RuleFor(s => s.Artist.MetadataProfileId).Cascade(CascadeMode.Stop)
+                .ValidId()
+                .SetValidator(metadataProfileExistsValidator)
+                .When(s => s.Artist != null);
+
+            PostValidator.RuleFor(s => s.Artist.Path).Cascade(CascadeMode.Stop)
+                .IsValidPath()
+                .SetValidator(rootFolderValidator)
+                .SetValidator(mappedNetworkDriveValidator)
+                .SetValidator(artistPathValidator)
+                .SetValidator(artistAncestorValidator)
+                .SetValidator(recycleBinValidator)
+                .SetValidator(systemFolderValidator)
+                .When(s => s.Artist != null && s.Artist.Path.IsNotNullOrWhiteSpace());
+
+            PostValidator.RuleFor(s => s.Artist.RootFolderPath)
+                .IsValidPath()
+                .SetValidator(rootFolderExistsValidator)
+                .When(s => s.Artist != null && s.Artist.Path.IsNullOrWhiteSpace());
         }
 
         [HttpGet]

src/Lidarr.Api.V1/Albums/AlbumResource.cs

@@ -110,8 +110,8 @@ namespace Lidarr.Api.V1.Albums
                 AlbumType = resource.AlbumType,
                 Monitored = resource.Monitored,
                 AnyReleaseOk = resource.AnyReleaseOk,
-                AlbumReleases = resource.Releases.ToModel(),
-                AddOptions = resource.AddOptions,
+                AlbumReleases = resource.Releases?.ToModel() ?? new List<AlbumRelease>(),
+                AddOptions = resource.AddOptions ?? new AddAlbumOptions(),
                 Artist = artist,
                 ArtistMetadata = artist.Metadata.Value
             };

src/NzbDrone.Core/Validation/Paths/AlbumExistsValidator.cs

@@ -0,0 +1,29 @@
+using FluentValidation.Validators;
+using NzbDrone.Core.Music;
+
+namespace NzbDrone.Core.Validation.Paths
+{
+    public class AlbumExistsValidator : PropertyValidator
+    {
+        private readonly IAlbumService _albumService;
+
+        public AlbumExistsValidator(IAlbumService albumService)
+        {
+            _albumService = albumService;
+        }
+
+        protected override string GetDefaultMessageTemplate() => "This album has already been added.";
+
+        protected override bool IsValid(PropertyValidatorContext context)
+        {
+            if (context.PropertyValue == null)
+            {
+                return true;
+            }
+
+            var foreignAlbumId = context.PropertyValue.ToString();
+
+            return _albumService.FindById(foreignAlbumId) == null;
+        }
+    }
+}