Dataflow_HomeController.cs

public class HomeController : Controller
    {
        private readonly BufferBlock<CompetitionEntry> _bufferBlock;
        private readonly ILogger<HomeController> _logger;

        public HomeController(BufferBlock<CompetitionEntry> bufferBlock, ILogger<HomeController> logger)
        {
            _bufferBlock = bufferBlock;
            _logger = logger;
        }

        public IActionResult Index()
        {
            return View();
        }

        [HttpPost("enter")]
        public async Task<IActionResult> SubmitEntry([FromBody] CompetitionEntryRequest entry)
        {
            // Sanitise the input
            entry.Email = entry.Email.Trim();
            
            // Create the object, from the model
            var newEntry = new CompetitionEntry
            {
                Email = entry.Email,
                Answer = entry.Answer,
                Created = DateTime.UtcNow,
                IPAddress = HttpContext.Connection.RemoteIpAddress ?? HttpContext.Connection.LocalIpAddress
            };

            // "Queue" the message on the Buffer Block
            await _bufferBlock.SendAsync(newEntry);

            return Ok();
        }
    }