fix adding single items to playlists (#2382)

CHANGELOG.md

@@ -10,6 +10,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 ### Fixed
 - Fix transcoding content with bt709/pc color metadata
 - Fix scripted schedule validation (file exists) when creating or editing playout
+- Fix adding single episode, movie, season, show to empty playlists
 
 ### Changed
 - **BREAKING CHANGE**: change how `Scripted Schedule` system works

ErsatzTV.Application/MediaCollections/Commands/AddEpisodeToPlaylistHandler.cs

@@ -20,9 +20,11 @@ public class AddEpisodeToPlaylistHandler(IDbContextFactory<TvContext> dbContextF
 
     private static async Task<Unit> ApplyAddEpisodeRequest(TvContext dbContext, Parameters parameters)
     {
+        int index = parameters.Playlist.Items.Count > 0 ? parameters.Playlist.Items.Max(i => i.Index) + 1 : 0;
+
         var playlistItem = new PlaylistItem
         {
-            Index = parameters.Playlist.Items.Max(i => i.Index) + 1,
+            Index = index,
             CollectionType = ProgramScheduleItemCollectionType.Episode,
             MediaItemId = parameters.Episode.Id,
             PlaybackOrder = PlaybackOrder.Shuffle,

ErsatzTV.Application/MediaCollections/Commands/AddMovieToPlaylistHandler.cs

@@ -20,9 +20,11 @@ public class AddMovieToPlaylistHandler(IDbContextFactory<TvContext> dbContextFac
 
     private static async Task<Unit> ApplyAddMovieRequest(TvContext dbContext, Parameters parameters)
     {
+        int index = parameters.Playlist.Items.Count > 0 ? parameters.Playlist.Items.Max(i => i.Index) + 1 : 0;
+
         var playlistItem = new PlaylistItem
         {
-            Index = parameters.Playlist.Items.Max(i => i.Index) + 1,
+            Index = index,
             CollectionType = ProgramScheduleItemCollectionType.Movie,
             MediaItemId = parameters.Movie.Id,
             PlaybackOrder = PlaybackOrder.Shuffle,

ErsatzTV.Application/MediaCollections/Commands/AddSeasonToPlaylistHandler.cs

@@ -20,9 +20,11 @@ public class AddSeasonToPlaylistHandler(IDbContextFactory<TvContext> dbContextFa
 
     private static async Task<Unit> ApplyAddSeasonRequest(TvContext dbContext, Parameters parameters)
     {
+        int index = parameters.Playlist.Items.Count > 0 ? parameters.Playlist.Items.Max(i => i.Index) + 1 : 0;
+
         var playlistItem = new PlaylistItem
         {
-            Index = parameters.Playlist.Items.Max(i => i.Index) + 1,
+            Index = index,
             CollectionType = ProgramScheduleItemCollectionType.TelevisionSeason,
             MediaItemId = parameters.Season.Id,
             PlaybackOrder = PlaybackOrder.Shuffle,

ErsatzTV.Application/MediaCollections/Commands/AddShowToPlaylistHandler.cs

@@ -20,9 +20,11 @@ public class AddShowToPlaylistHandler(IDbContextFactory<TvContext> dbContextFact
 
     private static async Task<Unit> ApplyAddShowRequest(TvContext dbContext, Parameters parameters)
     {
+        int index = parameters.Playlist.Items.Count > 0 ? parameters.Playlist.Items.Max(i => i.Index) + 1 : 0;
+
         var playlistItem = new PlaylistItem
         {
-            Index = parameters.Playlist.Items.Max(i => i.Index) + 1,
+            Index = index,
             CollectionType = ProgramScheduleItemCollectionType.TelevisionShow,
             MediaItemId = parameters.Show.Id,
             PlaybackOrder = PlaybackOrder.Shuffle,