todo.cs

public class TodoConverter : IStateConverter
{
    public Task<object> ConvertAsync(StateConverterContext context)
    {
        var urlHelper = context.HttpContext.RequestServices.GetRequiredService<IUrlHelper>();

        var todo = context.Object as TodoModel;

        var actions = new List<Siren.Core.Action>();
        actions.Add(new Siren.Core.Action
            {
                Name = "delete",
                Title = "Delete Todo",
                Method = "DELETE",
                Href = urlHelper.Action("Delete", "Todo"),
            });

        if (todo.IsCompleted == false)
        {
            actions.Add(
                new Siren.Core.Action
                {
                    Name = "complete",
                    Title = "Complete Todo",
                    Method = "PUT",
                    Href = urlHelper.Action("Complete", "Todo"),
                });
        }


        var document = new Document
        {
            Class = new Class { "todo" },
            Properties = todo,
            Href = urlHelper.Action("Get", "Todo"),
            Actions = new Actions(actions)
        };

        return Task.FromResult<object>(document);            
    }
}