New: MB ID filter when getting artist from API

Fixes #1200

Co-Authored-By: Mark McDowall <markus101@users.noreply.github.com>

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

@@ -1,3 +1,4 @@
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using FluentValidation;
@@ -122,8 +123,18 @@ namespace Lidarr.Api.V1.Artist
 
         private List<ArtistResource> AllArtists()
         {
+            var mbId = Request.GetGuidQueryParameter("mbId");
             var artistStats = _artistStatisticsService.ArtistStatistics();
-            var artistsResources = _artistService.GetAllArtists().ToResource();
+            var artistsResources = new List<ArtistResource>();
+
+            if (mbId != Guid.Empty)
+            {
+                artistsResources.AddIfNotNull(_artistService.FindById(mbId.ToString()).ToResource());
+            }
+            else
+            {
+                artistsResources.AddRange(_artistService.GetAllArtists().ToResource());
+            }
 
             MapCoversToLocal(artistsResources.ToArray());
             LinkNextPreviousAlbums(artistsResources.ToArray());

src/Lidarr.Http/Extensions/RequestExtensions.cs

@@ -54,5 +54,29 @@ namespace Lidarr.Http.Extensions
             return request.Path.StartsWith("/MediaCover/", StringComparison.InvariantCultureIgnoreCase) ||
                    request.Path.StartsWith("/Content/Images/", StringComparison.InvariantCultureIgnoreCase);
         }
+
+        public static int GetIntegerQueryParameter(this Request request, string parameter, int defaultValue = 0)
+        {
+            var parameterValue = request.Query[parameter];
+
+            if (parameterValue.HasValue)
+            {
+                return int.Parse(parameterValue.Value);
+            }
+
+            return defaultValue;
+        }
+
+        public static Guid GetGuidQueryParameter(this Request request, string parameter, Guid defaultValue = default)
+        {
+            var parameterValue = request.Query[parameter];
+
+            if (parameterValue.HasValue)
+            {
+                return Guid.Parse(parameterValue.Value);
+            }
+
+            return defaultValue;
+        }
     }
 }