WebAPISignalRChat/Backend/Diligent.WebAPI.Host/Hubs/ChatMessage.cs

namespace Diligent.WebAPI.Host.Hubs
{
    public class ChatMessage
    {
        public string? UserId { get; set; }
        public string? User { get; set; }
        public string Message { get; set; }
        public DateTime Created { get; set; } = DateTime.Now;
        public Attachment? Attachment { get; set; }

        // Context.ConnectionId generated by SignalR
        public string ConnId { get; set; }
    }
}