jellyfin/Jellyfin.Api/ModelBinders/NullableEnumModelBinderProvider.cs

using System;
using Microsoft.AspNetCore.Mvc.ModelBinding;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;

namespace Jellyfin.Api.ModelBinders
{
    /// <summary>
    /// Nullable enum model binder provider.
    /// </summary>
    public class NullableEnumModelBinderProvider : IModelBinderProvider
    {
        /// <inheritdoc />
        public IModelBinder? GetBinder(ModelBinderProviderContext context)
        {
            var nullableType = Nullable.GetUnderlyingType(context.Metadata.ModelType);
            if (nullableType is null || !nullableType.IsEnum)
            {
                // Type isn't nullable or isn't an enum.
                return null;
            }

            var logger = context.Services.GetRequiredService<ILogger<NullableEnumModelBinder>>();
            return new NullableEnumModelBinder(logger);
        }
    }
}