Use Guid as API parameter type where possible

Emby.Server.Implementations/Channels/ChannelManager.cs

@@ -538,20 +538,20 @@ namespace Emby.Server.Implementations.Channels
             return _libraryManager.GetItemIds(
                 new InternalItemsQuery
                 {
-                    IncludeItemTypes = new[] { nameof(Channel) },
-                    OrderBy = new[] { (ItemSortBy.SortName, SortOrder.Ascending) }
-                }).Select(i => GetChannelFeatures(i.ToString("N", CultureInfo.InvariantCulture))).ToArray();
+                    IncludeItemTypes = new[] {nameof(Channel)},
+                    OrderBy = new[] {(ItemSortBy.SortName, SortOrder.Ascending)}
+                }).Select(i => GetChannelFeatures(i)).ToArray();
         }
 
         /// <inheritdoc />
-        public ChannelFeatures GetChannelFeatures(string id)
+        public ChannelFeatures GetChannelFeatures(Guid? id)
         {
-            if (string.IsNullOrEmpty(id))
+            if (!id.HasValue)
             {
                 throw new ArgumentNullException(nameof(id));
             }
 
-            var channel = GetChannel(id);
+            var channel = GetChannel(id.Value);
             var channelProvider = GetChannelProvider(channel);
 
             return GetChannelFeaturesDto(channel, channelProvider, channelProvider.GetChannelFeatures());

Emby.Server.Implementations/Library/LibraryManager.cs

@@ -2474,6 +2474,21 @@ namespace Emby.Server.Implementations.Library
 
             return RootFolder;
         }
+        
+        public BaseItem GetParentItem(Guid? parentId, Guid? userId)
+        {
+            if (parentId.HasValue)
+            {
+                return GetItemById(parentId.Value);
+            }
+
+            if (userId.HasValue && userId != Guid.Empty)
+            {
+                return GetUserRootFolder();
+            }
+
+            return RootFolder;
+        }
 
         /// <inheritdoc />
         public bool IsVideoFile(string path)

Emby.Server.Implementations/Library/SearchEngine.cs

@@ -156,8 +156,8 @@ namespace Emby.Server.Implementations.Library
                 ExcludeItemTypes = excludeItemTypes.ToArray(),
                 IncludeItemTypes = includeItemTypes.ToArray(),
                 Limit = query.Limit,
-                IncludeItemsByName = string.IsNullOrEmpty(query.ParentId),
-                ParentId = string.IsNullOrEmpty(query.ParentId) ? Guid.Empty : new Guid(query.ParentId),
+                IncludeItemsByName = query.ParentId.HasValue,
+                ParentId = query.ParentId ?? Guid.Empty,
                 OrderBy = new[] { (ItemSortBy.SortName, SortOrder.Ascending) },
                 Recursive = true,
 

Emby.Server.Implementations/TV/TVSeriesManager.cs

@@ -56,13 +56,11 @@ namespace Emby.Server.Implementations.TV
                 return GetResult(GetNextUpEpisodes(request, user, new[] { presentationUniqueKey }, dtoOptions), request);
             }
 
-            var parentIdGuid = string.IsNullOrEmpty(request.ParentId) ? (Guid?)null : new Guid(request.ParentId);
-
             BaseItem[] parents;
 
-            if (parentIdGuid.HasValue)
+            if (request.ParentId.HasValue)
             {
-                var parent = _libraryManager.GetItemById(parentIdGuid.Value);
+                var parent = _libraryManager.GetItemById(request.ParentId.Value);
 
                 if (parent != null)
                 {

Jellyfin.Api/Controllers/ArtistsController.cs

@@ -3,7 +3,6 @@ using System.ComponentModel.DataAnnotations;
 using System.Linq;
 using Jellyfin.Api.Constants;
 using Jellyfin.Api.Extensions;
-using Jellyfin.Api.Helpers;
 using Jellyfin.Api.ModelBinders;
 using Jellyfin.Data.Entities;
 using MediaBrowser.Controller.Dto;
@@ -87,7 +86,7 @@ namespace Jellyfin.Api.Controllers
             [FromQuery] int? startIndex,
             [FromQuery] int? limit,
             [FromQuery] string? searchTerm,
-            [FromQuery] string? parentId,
+            [FromQuery] Guid? parentId,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ItemFields[] fields,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] excludeItemTypes,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] includeItemTypes,
@@ -124,11 +123,11 @@ namespace Jellyfin.Api.Controllers
             if (userId.HasValue && !userId.Equals(Guid.Empty))
             {
                 user = _userManager.GetUserById(userId.Value);
-                parentItem = string.IsNullOrEmpty(parentId) ? _libraryManager.GetUserRootFolder() : _libraryManager.GetItemById(parentId);
+                parentItem = parentId.HasValue ? _libraryManager.GetItemById(parentId.Value) : _libraryManager.GetUserRootFolder();
             }
             else
             {
-                parentItem = string.IsNullOrEmpty(parentId) ? _libraryManager.RootFolder : _libraryManager.GetItemById(parentId);
+                parentItem = parentId.HasValue ? _libraryManager.GetItemById(parentId.Value) : _libraryManager.RootFolder;
             }
 
             var query = new InternalItemsQuery(user)
@@ -157,15 +156,15 @@ namespace Jellyfin.Api.Controllers
                 EnableTotalRecordCount = enableTotalRecordCount
             };
 
-            if (!string.IsNullOrWhiteSpace(parentId))
+            if (parentId.HasValue)
             {
                 if (parentItem is Folder)
                 {
-                    query.AncestorIds = new[] { new Guid(parentId) };
+                    query.AncestorIds = new[] { parentId.Value };
                 }
                 else
                 {
-                    query.ItemIds = new[] { new Guid(parentId) };
+                    query.ItemIds = new[] { parentId.Value };
                 }
             }
 
@@ -291,7 +290,7 @@ namespace Jellyfin.Api.Controllers
             [FromQuery] int? startIndex,
             [FromQuery] int? limit,
             [FromQuery] string? searchTerm,
-            [FromQuery] string? parentId,
+            [FromQuery] Guid? parentId,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ItemFields[] fields,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] excludeItemTypes,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] includeItemTypes,
@@ -328,11 +327,11 @@ namespace Jellyfin.Api.Controllers
             if (userId.HasValue && !userId.Equals(Guid.Empty))
             {
                 user = _userManager.GetUserById(userId.Value);
-                parentItem = string.IsNullOrEmpty(parentId) ? _libraryManager.GetUserRootFolder() : _libraryManager.GetItemById(parentId);
+                parentItem = parentId.HasValue ? _libraryManager.GetItemById(parentId.Value) : _libraryManager.GetUserRootFolder();
             }
             else
             {
-                parentItem = string.IsNullOrEmpty(parentId) ? _libraryManager.RootFolder : _libraryManager.GetItemById(parentId);
+                parentItem = parentId.HasValue ? _libraryManager.GetItemById(parentId.Value) : _libraryManager.RootFolder;
             }
 
             var query = new InternalItemsQuery(user)
@@ -361,15 +360,15 @@ namespace Jellyfin.Api.Controllers
                 EnableTotalRecordCount = enableTotalRecordCount
             };
 
-            if (!string.IsNullOrWhiteSpace(parentId))
+            if (parentId.HasValue)
             {
                 if (parentItem is Folder)
                 {
-                    query.AncestorIds = new[] { new Guid(parentId) };
+                    query.AncestorIds = new[] { parentId.Value };
                 }
                 else
                 {
-                    query.ItemIds = new[] { new Guid(parentId) };
+                    query.ItemIds = new[] { parentId.Value };
                 }
             }
 

Jellyfin.Api/Controllers/ChannelsController.cs

@@ -92,7 +92,7 @@ namespace Jellyfin.Api.Controllers
         /// <response code="200">Channel features returned.</response>
         /// <returns>An <see cref="OkResult"/> containing the channel features.</returns>
         [HttpGet("{channelId}/Features")]
-        public ActionResult<ChannelFeatures> GetChannelFeatures([FromRoute, Required] string channelId)
+        public ActionResult<ChannelFeatures> GetChannelFeatures([FromRoute, Required] Guid channelId)
         {
             return _channelManager.GetChannelFeatures(channelId);
         }

Jellyfin.Api/Controllers/FilterController.cs

@@ -50,13 +50,13 @@ namespace Jellyfin.Api.Controllers
         [ProducesResponseType(StatusCodes.Status200OK)]
         public ActionResult<QueryFiltersLegacy> GetQueryFiltersLegacy(
             [FromQuery] Guid? userId,
-            [FromQuery] string? parentId,
+            [FromQuery] Guid? parentId,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] includeItemTypes,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] mediaTypes)
         {
-            var parentItem = string.IsNullOrEmpty(parentId)
-                ? null
-                : _libraryManager.GetItemById(parentId);
+            var parentItem = parentId.HasValue
+                ? _libraryManager.GetItemById(parentId.Value)
+                : null;
 
             var user = userId.HasValue && !userId.Equals(Guid.Empty)
                 ? _userManager.GetUserById(userId.Value)
@@ -71,11 +71,11 @@ namespace Jellyfin.Api.Controllers
                 parentItem = null;
             }
 
-            var item = string.IsNullOrEmpty(parentId)
-                ? user == null
+            var item = parentId.HasValue
+                ? parentItem
+                : user == null
                     ? _libraryManager.RootFolder
-                    : _libraryManager.GetUserRootFolder()
-                : parentItem;
+                    : _libraryManager.GetUserRootFolder();
 
             var query = new InternalItemsQuery
             {
@@ -140,7 +140,7 @@ namespace Jellyfin.Api.Controllers
         [ProducesResponseType(StatusCodes.Status200OK)]
         public ActionResult<QueryFilters> GetQueryFilters(
             [FromQuery] Guid? userId,
-            [FromQuery] string? parentId,
+            [FromQuery] Guid? parentId,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] includeItemTypes,
             [FromQuery] bool? isAiring,
             [FromQuery] bool? isMovie,
@@ -150,9 +150,9 @@ namespace Jellyfin.Api.Controllers
             [FromQuery] bool? isSeries,
             [FromQuery] bool? recursive)
         {
-            var parentItem = string.IsNullOrEmpty(parentId)
-                ? null
-                : _libraryManager.GetItemById(parentId);
+            var parentItem = parentId.HasValue
+                ? _libraryManager.GetItemById(parentId.Value)
+                : null;
 
             var user = userId.HasValue && !userId.Equals(Guid.Empty)
                 ? _userManager.GetUserById(userId.Value)

Jellyfin.Api/Controllers/GenresController.cs

@@ -72,7 +72,7 @@ namespace Jellyfin.Api.Controllers
             [FromQuery] int? startIndex,
             [FromQuery] int? limit,
             [FromQuery] string? searchTerm,
-            [FromQuery] string? parentId,
+            [FromQuery] Guid? parentId,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ItemFields[] fields,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] excludeItemTypes,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] includeItemTypes,
@@ -109,15 +109,15 @@ namespace Jellyfin.Api.Controllers
                 EnableTotalRecordCount = enableTotalRecordCount
             };
 
-            if (!string.IsNullOrWhiteSpace(parentId))
+            if (parentId.HasValue)
             {
                 if (parentItem is Folder)
                 {
-                    query.AncestorIds = new[] { new Guid(parentId) };
+                    query.AncestorIds = new[] { parentId.Value };
                 }
                 else
                 {
-                    query.ItemIds = new[] { new Guid(parentId) };
+                    query.ItemIds = new[] { parentId.Value };
                 }
             }
 

Jellyfin.Api/Controllers/ItemsController.cs

@@ -176,7 +176,7 @@ namespace Jellyfin.Api.Controllers
             [FromQuery] bool? recursive,
             [FromQuery] string? searchTerm,
             [FromQuery] string? sortOrder,
-            [FromQuery] string? parentId,
+            [FromQuery] Guid? parentId,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ItemFields[] fields,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] excludeItemTypes,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] includeItemTypes,
@@ -241,9 +241,9 @@ namespace Jellyfin.Api.Controllers
 
             BaseItem? item = null;
             QueryResult<BaseItem> result;
-            if (!string.IsNullOrEmpty(parentId))
+            if (parentId.HasValue)
             {
-                item = _libraryManager.GetItemById(parentId);
+                item = _libraryManager.GetItemById(parentId.Value);
             }
 
             item ??= _libraryManager.GetUserRootFolder();
@@ -343,7 +343,7 @@ namespace Jellyfin.Api.Controllers
                     ItemIds = ids,
                     MinCommunityRating = minCommunityRating,
                     MinCriticRating = minCriticRating,
-                    ParentId = string.IsNullOrWhiteSpace(parentId) ? Guid.Empty : new Guid(parentId),
+                    ParentId = parentId ?? Guid.Empty,
                     ParentIndexNumber = parentIndexNumber,
                     EnableTotalRecordCount = enableTotalRecordCount,
                     ExcludeItemIds = excludeItemIds,
@@ -615,7 +615,7 @@ namespace Jellyfin.Api.Controllers
             [FromQuery] bool? recursive,
             [FromQuery] string? searchTerm,
             [FromQuery] string? sortOrder,
-            [FromQuery] string? parentId,
+            [FromQuery] Guid? parentId,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ItemFields[] fields,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] excludeItemTypes,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] includeItemTypes,
@@ -773,7 +773,7 @@ namespace Jellyfin.Api.Controllers
             [FromQuery] int? startIndex,
             [FromQuery] int? limit,
             [FromQuery] string? searchTerm,
-            [FromQuery] string? parentId,
+            [FromQuery] Guid? parentId,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ItemFields[] fields,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] mediaTypes,
             [FromQuery] bool? enableUserData,
@@ -785,7 +785,7 @@ namespace Jellyfin.Api.Controllers
             [FromQuery] bool? enableImages = true)
         {
             var user = _userManager.GetUserById(userId);
-            var parentIdGuid = string.IsNullOrWhiteSpace(parentId) ? Guid.Empty : new Guid(parentId);
+            var parentIdGuid = parentId ?? Guid.Empty;
             var dtoOptions = new DtoOptions { Fields = fields }
                 .AddClientFields(Request)
                 .AddAdditionalDtoOptions(enableImages, enableUserData, imageTypeLimit, enableImageTypes);

Jellyfin.Api/Controllers/LibraryController.cs

@@ -362,7 +362,7 @@ namespace Jellyfin.Api.Controllers
         [Authorize(Policy = Policies.DefaultAuthorization)]
         [ProducesResponseType(StatusCodes.Status204NoContent)]
         [ProducesResponseType(StatusCodes.Status401Unauthorized)]
-        public ActionResult DeleteItems([FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] ids)
+        public ActionResult DeleteItems([FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] Guid[] ids)
         {
             if (ids.Length == 0)
             {

Jellyfin.Api/Controllers/MoviesController.cs

@@ -65,7 +65,7 @@ namespace Jellyfin.Api.Controllers
         [HttpGet("Recommendations")]
         public ActionResult<IEnumerable<RecommendationDto>> GetMovieRecommendations(
             [FromQuery] Guid? userId,
-            [FromQuery] string? parentId,
+            [FromQuery] Guid? parentId,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ItemFields[] fields,
             [FromQuery] int categoryLimit = 5,
             [FromQuery] int itemLimit = 8)
@@ -78,7 +78,7 @@ namespace Jellyfin.Api.Controllers
 
             var categories = new List<RecommendationDto>();
 
-            var parentIdGuid = string.IsNullOrWhiteSpace(parentId) ? Guid.Empty : new Guid(parentId);
+            var parentIdGuid = parentId ?? Guid.Empty;
 
             var query = new InternalItemsQuery(user)
             {

Jellyfin.Api/Controllers/MusicGenresController.cs

@@ -72,7 +72,7 @@ namespace Jellyfin.Api.Controllers
             [FromQuery] int? startIndex,
             [FromQuery] int? limit,
             [FromQuery] string? searchTerm,
-            [FromQuery] string? parentId,
+            [FromQuery] Guid? parentId,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ItemFields[] fields,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] excludeItemTypes,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] includeItemTypes,
@@ -109,15 +109,15 @@ namespace Jellyfin.Api.Controllers
                 EnableTotalRecordCount = enableTotalRecordCount
             };
 
-            if (!string.IsNullOrWhiteSpace(parentId))
+            if (parentId.HasValue)
             {
                 if (parentItem is Folder)
                 {
-                    query.AncestorIds = new[] { new Guid(parentId) };
+                    query.AncestorIds = new[] { parentId.Value };
                 }
                 else
                 {
-                    query.ItemIds = new[] { new Guid(parentId) };
+                    query.ItemIds = new[] { parentId.Value };
                 }
             }
 

Jellyfin.Api/Controllers/PackageController.cs

@@ -45,13 +45,13 @@ namespace Jellyfin.Api.Controllers
         [ProducesResponseType(StatusCodes.Status200OK)]
         public async Task<ActionResult<PackageInfo>> GetPackageInfo(
             [FromRoute, Required] string name,
-            [FromQuery] string? assemblyGuid)
+            [FromQuery] Guid? assemblyGuid)
         {
             var packages = await _installationManager.GetAvailablePackages().ConfigureAwait(false);
             var result = _installationManager.FilterPackages(
                     packages,
                     name,
-                    string.IsNullOrEmpty(assemblyGuid) ? default : Guid.Parse(assemblyGuid))
+                    assemblyGuid ?? default)
                 .FirstOrDefault();
 
             if (result == null)
@@ -92,7 +92,7 @@ namespace Jellyfin.Api.Controllers
         [Authorize(Policy = Policies.RequiresElevation)]
         public async Task<ActionResult> InstallPackage(
             [FromRoute, Required] string name,
-            [FromQuery] string? assemblyGuid,
+            [FromQuery] Guid? assemblyGuid,
             [FromQuery] string? version,
             [FromQuery] string? repositoryUrl)
         {
@@ -106,7 +106,7 @@ namespace Jellyfin.Api.Controllers
             var package = _installationManager.GetCompatibleVersions(
                     packages,
                     name,
-                    string.IsNullOrEmpty(assemblyGuid) ? Guid.Empty : Guid.Parse(assemblyGuid),
+                    assemblyGuid ?? Guid.Empty,
                     specificVersion: string.IsNullOrEmpty(version) ? null : Version.Parse(version))
                 .FirstOrDefault();
 

Jellyfin.Api/Controllers/PersonsController.cs

@@ -79,7 +79,7 @@ namespace Jellyfin.Api.Controllers
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ImageType[] enableImageTypes,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] excludePersonTypes,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] personTypes,
-            [FromQuery] string? appearsInItemId,
+            [FromQuery] Guid? appearsInItemId,
             [FromQuery] Guid? userId,
             [FromQuery] bool? enableImages = true)
         {
@@ -102,7 +102,7 @@ namespace Jellyfin.Api.Controllers
                 NameContains = searchTerm,
                 User = user,
                 IsFavorite = !isFavorite.HasValue && isFavoriteInFilters ? true : isFavorite,
-                AppearsInItemId = string.IsNullOrEmpty(appearsInItemId) ? Guid.Empty : Guid.Parse(appearsInItemId),
+                AppearsInItemId = appearsInItemId ?? Guid.Empty,
                 Limit = limit ?? 0
             });
 

Jellyfin.Api/Controllers/SearchController.cs

@@ -86,7 +86,7 @@ namespace Jellyfin.Api.Controllers
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] includeItemTypes,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] excludeItemTypes,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] mediaTypes,
-            [FromQuery] string? parentId,
+            [FromQuery] Guid? parentId,
             [FromQuery] bool? isMovie,
             [FromQuery] bool? isSeries,
             [FromQuery] bool? isNews,

Jellyfin.Api/Controllers/StudiosController.cs

@@ -71,7 +71,7 @@ namespace Jellyfin.Api.Controllers
             [FromQuery] int? startIndex,
             [FromQuery] int? limit,
             [FromQuery] string? searchTerm,
-            [FromQuery] string? parentId,
+            [FromQuery] Guid? parentId,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ItemFields[] fields,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] excludeItemTypes,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] includeItemTypes,
@@ -109,15 +109,15 @@ namespace Jellyfin.Api.Controllers
                 EnableTotalRecordCount = enableTotalRecordCount
             };
 
-            if (!string.IsNullOrWhiteSpace(parentId))
+            if (parentId.HasValue)
             {
                 if (parentItem is Folder)
                 {
-                    query.AncestorIds = new[] { new Guid(parentId) };
+                    query.AncestorIds = new[] { parentId.Value };
                 }
                 else
                 {
-                    query.ItemIds = new[] { new Guid(parentId) };
+                    query.ItemIds = new[] { parentId.Value };
                 }
             }
 

Jellyfin.Api/Controllers/TrailersController.cs

@@ -145,7 +145,7 @@ namespace Jellyfin.Api.Controllers
             [FromQuery] bool? recursive,
             [FromQuery] string? searchTerm,
             [FromQuery] string? sortOrder,
-            [FromQuery] string? parentId,
+            [FromQuery] Guid? parentId,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ItemFields[] fields,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] excludeItemTypes,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ItemFilter[] filters,

Jellyfin.Api/Controllers/TvShowsController.cs

@@ -76,7 +76,7 @@ namespace Jellyfin.Api.Controllers
             [FromQuery] int? limit,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ItemFields[] fields,
             [FromQuery] string? seriesId,
-            [FromQuery] string? parentId,
+            [FromQuery] Guid? parentId,
             [FromQuery] bool? enableImges,
             [FromQuery] int? imageTypeLimit,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ImageType[] enableImageTypes,
@@ -132,7 +132,7 @@ namespace Jellyfin.Api.Controllers
             [FromQuery] int? startIndex,
             [FromQuery] int? limit,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ItemFields[] fields,
-            [FromQuery] string? parentId,
+            [FromQuery] Guid? parentId,
             [FromQuery] bool? enableImges,
             [FromQuery] int? imageTypeLimit,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ImageType[] enableImageTypes,
@@ -144,7 +144,7 @@ namespace Jellyfin.Api.Controllers
 
             var minPremiereDate = DateTime.Now.Date.ToUniversalTime().AddDays(-1);
 
-            var parentIdGuid = string.IsNullOrWhiteSpace(parentId) ? Guid.Empty : new Guid(parentId);
+            var parentIdGuid = parentId ?? Guid.Empty;
 
             var options = new DtoOptions { Fields = fields }
                 .AddClientFields(Request)
@@ -194,14 +194,14 @@ namespace Jellyfin.Api.Controllers
         [ProducesResponseType(StatusCodes.Status200OK)]
         [ProducesResponseType(StatusCodes.Status404NotFound)]
         public ActionResult<QueryResult<BaseItemDto>> GetEpisodes(
-            [FromRoute, Required] string seriesId,
+            [FromRoute, Required] Guid seriesId,
             [FromQuery] Guid? userId,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ItemFields[] fields,
             [FromQuery] int? season,
-            [FromQuery] string? seasonId,
+            [FromQuery] Guid? seasonId,
             [FromQuery] bool? isMissing,
             [FromQuery] string? adjacentTo,
-            [FromQuery] string? startItemId,
+            [FromQuery] Guid? startItemId,
             [FromQuery] int? startIndex,
             [FromQuery] int? limit,
             [FromQuery] bool? enableImages,
@@ -220,9 +220,9 @@ namespace Jellyfin.Api.Controllers
                 .AddClientFields(Request)
                 .AddAdditionalDtoOptions(enableImages, enableUserData, imageTypeLimit, enableImageTypes!);
 
-            if (!string.IsNullOrWhiteSpace(seasonId)) // Season id was supplied. Get episodes by season id.
+            if (seasonId.HasValue) // Season id was supplied. Get episodes by season id.
             {
-                var item = _libraryManager.GetItemById(new Guid(seasonId));
+                var item = _libraryManager.GetItemById(seasonId.Value);
                 if (!(item is Season seasonItem))
                 {
                     return NotFound("No season exists with Id " + seasonId);
@@ -264,10 +264,10 @@ namespace Jellyfin.Api.Controllers
                     .ToList();
             }
 
-            if (!string.IsNullOrWhiteSpace(startItemId))
+            if (startItemId.HasValue)
             {
                 episodes = episodes
-                    .SkipWhile(i => !string.Equals(i.Id.ToString("N", CultureInfo.InvariantCulture), startItemId, StringComparison.OrdinalIgnoreCase))
+                    .SkipWhile(i => startItemId.Value.Equals(i.Id))
                     .ToList();
             }
 
@@ -316,7 +316,7 @@ namespace Jellyfin.Api.Controllers
         [ProducesResponseType(StatusCodes.Status200OK)]
         [ProducesResponseType(StatusCodes.Status404NotFound)]
         public ActionResult<QueryResult<BaseItemDto>> GetSeasons(
-            [FromRoute, Required] string seriesId,
+            [FromRoute, Required] Guid seriesId,
             [FromQuery] Guid? userId,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ItemFields[] fields,
             [FromQuery] bool? isSpecialSeason,

Jellyfin.Api/Controllers/YearsController.cs

@@ -71,7 +71,7 @@ namespace Jellyfin.Api.Controllers
             [FromQuery] int? startIndex,
             [FromQuery] int? limit,
             [FromQuery] string? sortOrder,
-            [FromQuery] string? parentId,
+            [FromQuery] Guid? parentId,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ItemFields[] fields,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] excludeItemTypes,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] includeItemTypes,
@@ -94,11 +94,11 @@ namespace Jellyfin.Api.Controllers
             if (userId.HasValue && !userId.Equals(Guid.Empty))
             {
                 user = _userManager.GetUserById(userId.Value);
-                parentItem = string.IsNullOrEmpty(parentId) ? _libraryManager.GetUserRootFolder() : _libraryManager.GetItemById(parentId);
+                parentItem = parentId.HasValue ? _libraryManager.GetItemById(parentId.Value) : _libraryManager.GetUserRootFolder();
             }
             else
             {
-                parentItem = string.IsNullOrEmpty(parentId) ? _libraryManager.RootFolder : _libraryManager.GetItemById(parentId);
+                parentItem = parentId.HasValue ? _libraryManager.GetItemById(parentId.Value) : _libraryManager.RootFolder;
             }
 
             IList<BaseItem> items;

MediaBrowser.Controller/Channels/IChannelManager.cs

@@ -24,7 +24,7 @@ namespace MediaBrowser.Controller.Channels
         /// </summary>
         /// <param name="id">The identifier.</param>
         /// <returns>ChannelFeatures.</returns>
-        ChannelFeatures GetChannelFeatures(string id);
+        ChannelFeatures GetChannelFeatures(Guid? id);
 
         /// <summary>
         /// Gets all channel features.

MediaBrowser.Controller/Library/ILibraryManager.cs

@@ -574,5 +574,7 @@ namespace MediaBrowser.Controller.Library
         void RunMetadataSavers(IReadOnlyList<BaseItem> items, ItemUpdateType updateReason);
 
         BaseItem GetParentItem(string parentId, Guid? userId);
+
+        BaseItem GetParentItem(Guid? parentId, Guid? userId);
     }
 }

MediaBrowser.Model/Querying/NextUpQuery.cs

@@ -18,7 +18,7 @@ namespace MediaBrowser.Model.Querying
         /// Gets or sets the parent identifier.
         /// </summary>
         /// <value>The parent identifier.</value>
-        public string ParentId { get; set; }
+        public Guid? ParentId { get; set; }
 
         /// <summary>
         /// Gets or sets the series id.

MediaBrowser.Model/Search/SearchQuery.cs

@@ -47,7 +47,7 @@ namespace MediaBrowser.Model.Search
 
         public string[] ExcludeItemTypes { get; set; }
 
-        public string ParentId { get; set; }
+        public Guid? ParentId { get; set; }
 
         public bool? IsMovie { get; set; }