Error sending object to .net signalr client

问题

My understanding is that with signalr I can just send objects back and forth. I am trying to set up a .net client to receive notifications that orders have been placed on a web site. I am trying to set up a very simple example so that I understand the concepts. It works great when I am sending a string notification back to the client, but when I try to send an object I get an error:

Microsoft.CSharp.RuntimeBinder.RuntimeBinderException was unhandled by user code
  HResult=-2146233088
  Message=The best overloaded method match for 'ConsoleHub.Program.DisplayOrder(ConsoleHub.Order)' has some invalid arguments
  Source=Anonymously Hosted DynamicMethods Assembly
  StackTrace:
       at CallSite.Target(Closure , CallSite , Type , Object )
       at System.Dynamic.UpdateDelegates.UpdateAndExecuteVoid2[T0,T1](CallSite site, T0 arg0, T1 arg1)
       at ConsoleHub.Program.<Main>b__6(Object o) in c:\Working\OrderNotifier\ConsoleHub\Program.cs:line 23
       at Microsoft.AspNet.SignalR.Client.Hubs.HubProxyExtensions.<>c__DisplayClass6`1.<On>b__4(JToken[] args)
       at Microsoft.AspNet.SignalR.Client.Hubs.Subscription.OnData(JToken[] data)
       at Microsoft.AspNet.SignalR.Client.Hubs.HubProxy.InvokeEvent(String eventName, JToken[] args)
       at Microsoft.AspNet.SignalR.Client.Hubs.HubConnection.OnReceived(JToken message)
       at Microsoft.AspNet.SignalR.Client.Connection.Microsoft.AspNet.SignalR.Client.IConnection.OnReceived(JToken message)
       at Microsoft.AspNet.SignalR.Client.Transports.HttpBasedTransport.ProcessResponse(IConnection connection, String response, Boolean& timedOut, Boolean& disconnected)
  InnerException:

My class:

public class Order
{
    public int OrderId { get; set; }
    public string Name { get; set; }
    public string OrderItem { get; set; }
}

My hub:

using Microsoft.AspNet.SignalR.Hubs;
using OrderNotifier.Models;
using System.Linq;
using System.Threading.Tasks;

namespace OrderNotifier.Hubs
{

    public class NotifierHub : Hub
    {
        OrderContext db = new OrderContext();

        public void Hello()
        {
            Clients.Caller.Welcome("hello");
        }

    }
}

My controller action:

    [HttpPost]
    public ActionResult Create(Order order)
    {
        if (ModelState.IsValid)
        {
            db.Orders.Add(order);
            db.SaveChanges();

            SendNotifier.SendOrderNotification(String.Format("{0} ordered {1}", order.Name, order.OrderItem), order);
            return RedirectToAction("Index");
        }

        return View(order);
    }

SendNotifier - which is a little weird because I am having it send both a string version and an object version for testing:

public class SendNotifier
{
    public static void SendOrderNotification(string message, Order order)
    {
        var context = GlobalHost.ConnectionManager.GetHubContext<NotifierHub>();
        context.Clients.All.Notify(message);
        context.Clients.All.Order(order);
    }
}

And my console application:

using Microsoft.AspNet.SignalR.Client.Hubs;
using OrderNotifier.Models;
using System;


namespace ConsoleHub
{
    class Program
    {
        static void Main(string[] args)
        {
            var hubConnection = new HubConnection("http://localhost:60692");

            var order = hubConnection.CreateHubProxy("NotifierHub");

            //
            // Set up action handlers
            //
            order.On("Welcome", message => Console.WriteLine(message));
            order.On("Notify", message => Console.WriteLine(message));
            order.On("Order", o => DisplayOrder(o));
            hubConnection.Start().Wait();

            order.Invoke("Hello").Wait();


            Console.WriteLine("Initialized...");
            Console.ReadLine();
        }


        public void DisplayOrder(Order o)
        {
            Console.WriteLine(String.Format("Order object received.../r/nOrderId: {0}/r/nName: {1}/r/nOrderItem: {2}", o.OrderId, o.Name, o.OrderItem));
            //Console.WriteLine(o);
        }
    }
}

If I change the DisplayOrder parameter to be a string it works. I know I could probably manually deserialize it using Json.Net, but my understanding is that I should just be able to work with it as an object and let signalr deserialize. What am I missing?

回答1:

You're using the dynamic object overload of On. You need to specify the type:

order.On<Order>("Order", DisplayOrder);

来源：https://stackoverflow.com/questions/13749897/error-sending-object-to-net-signalr-client

标签

signalr

signalr.client