Clean up EnumFlags serialization

src/Jellyfin.Extensions/Json/Converters/JsonFlagEnumConverter.cs

@@ -0,0 +1,36 @@
+using System;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace Jellyfin.Extensions.Json.Converters;
+
+/// <summary>
+/// Enum flag to json array converter.
+/// </summary>
+/// <typeparam name="T">The type of enum.</typeparam>
+public class JsonFlagEnumConverter<T> : JsonConverter<T>
+    where T : Enum
+{
+    private static readonly T[] _enumValues = (T[])Enum.GetValues(typeof(T));
+
+    /// <inheritdoc />
+    public override T Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
+    {
+        throw new NotImplementedException();
+    }
+
+    /// <inheritdoc />
+    public override void Write(Utf8JsonWriter writer, T value, JsonSerializerOptions options)
+    {
+        writer.WriteStartArray();
+        foreach (var enumValue in _enumValues)
+        {
+            if (value.HasFlag(enumValue))
+            {
+                writer.WriteStringValue(enumValue.ToString());
+            }
+        }
+
+        writer.WriteEndArray();
+    }
+}

src/Jellyfin.Extensions/Json/Converters/JsonFlagEnumConverterFactory.cs

@@ -0,0 +1,24 @@
+using System;
+using System.Reflection;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace Jellyfin.Extensions.Json.Converters;
+
+/// <summary>
+/// Json flag enum converter factory.
+/// </summary>
+public class JsonFlagEnumConverterFactory : JsonConverterFactory
+{
+    /// <inheritdoc />
+    public override bool CanConvert(Type typeToConvert)
+    {
+        return typeToConvert.IsEnum && typeToConvert.IsDefined(typeof(FlagsAttribute));
+    }
+
+    /// <inheritdoc />
+    public override JsonConverter? CreateConverter(Type typeToConvert, JsonSerializerOptions options)
+    {
+        return (JsonConverter?)Activator.CreateInstance(typeof(JsonFlagEnumConverter<>).MakeGenericType(typeToConvert));
+    }
+}

src/Jellyfin.Extensions/Json/JsonDefaults.cs

@@ -36,6 +36,7 @@ namespace Jellyfin.Extensions.Json
                 new JsonGuidConverter(),
                 new JsonNullableGuidConverter(),
                 new JsonVersionConverter(),
+                new JsonFlagEnumConverterFactory(),
                 new JsonStringEnumConverter(),
                 new JsonNullableStructConverterFactory(),
                 new JsonBoolNumberConverter(),