SignalR client side receives calls from dashboard client but not ecommerce client

Question

I have 2 Vue.js clients that share the same backend server (ASP.NET Core). One of the clients is an e-commerce site, and the other client is the admin dashboard that manages the orders.

I have implemented SignalR to allow live order updates on the order dashboard table. The updates currently work in real time without the need to refresh the browser when I update an order's status on the admin dashboard, eg when updating from "Out for Delivery" to "Delivered" on browser 1, browser 2 displays the changes immediately without having to refresh the page.

Order updated via dashboard, SignalR event received

However, when I create a new order from the e-commerce site, even though I have checked that my code enters the Hub method to broadcast the event and the new order details to all clients, the order dashboard does not update/refresh, and it does not receive any events as well when I checked the dev tools. I would appreciate some help on this problem.

Hub methods in mounted()

    // Establish hub connection
    this.connection = await OrderHub.connectToOrderHub();

    // Establish hub methods
    this.connection.on("OneOrder", order => {
      console.log("OneOrder called");
      console.log(order);
      this.getAllOrders();
    });

    this.connection.on("MultipleOrders", orders => {
      console.log("MultipleOrders called");
      console.log(orders);
      this.getAllOrders();
    });

    // start the connection
    this.connection
      .start()
      .then(() => {
        console.log("Connection to hub started");
      })
      .catch(err => console.log(err));

orderHub.js

const signalR = require("@aspnet/signalr");

class OrderHub {
  async connectToOrderHub() {
    return new signalR.HubConnectionBuilder()
      .withUrl("https://localhost:44393/order-hub")
      .configureLogging(signalR.LogLevel.Error)
      .build();
  }
}
export default new OrderHub();

OrderHub.cs in server side

public interface IOrderHub
    {
        Task NotifyOneChange(Order newOrder);
        Task NotifyMultipleChanges(List<Order> newOrders);
    }

    public class OrderHub : Hub, IOrderHub
    {
        private readonly IHubContext<OrderHub> _hubContext;

        public OrderHub(IHubContext<OrderHub> hubContext)
        {
            _hubContext = hubContext;
        }

        public async Task NotifyOneChange(Order newOrder)
        {
            await _hubContext.Clients.All.SendAsync("OneOrder", newOrder);
        }

        public async Task NotifyMultipleChanges(List<Order> newOrders)
        {
            await _hubContext.Clients.All.SendAsync("MultipleOrders", newOrders);
        }
    }

Create Order method

public async Task<Order> Create(Order order)
        {
            Order newOrder;
            try
            {
                List<string> imgKeys = new List<string>();
                foreach (OrderItem item in order.OrderItems)
                {
                    imgKeys.Add(item.OrderImageKey);
                }

                // make images on s3 permanent
                List<string> imgUrls = await _s3Service.CopyImagesAsync(imgKeys);

                // put the new images url into object
                for (int i = 0; i < order.OrderItems.Count; i++)
                {
                    order.OrderItems.ElementAt(i).OrderImageUrl = imgUrls.ElementAt(i);
                }

                // create new order object to be added
                newOrder = new Order()
                {
                    CreatedAt = DateTime.Now,
                    UpdatedAt = DateTime.Now,
                    OrderSubtotal = decimal.Parse(order.OrderSubtotal.ToString()),
                    OrderTotal = decimal.Parse(order.OrderTotal.ToString()),
                    ReferenceNo = order.ReferenceNo,
                    Request = order.Request,
                    Email = EncryptString(order.EmailString, encryptionKey),
                    UpdatedById = order.UpdatedById,
                    DeliveryTypeId = order.DeliveryTypeId,
                    Address = order.Address,
                    StatusId = 1,
                    OrderItems = order.OrderItems
                };

                // add to database
                await _context.Orders.AddAsync(newOrder);
                await _context.SaveChangesAsync();
            }
            catch (Exception ex)
            {
                throw new AppException("Unable to create product record.", new { message = ex.Message });
            }
            await _orderHub.NotifyOneChange(newOrder); // it steps inside & executes the method, but client side does not receive any events
            // returns product once done
            return newOrder;
        }

Answer 1

I managed to figure out the cause of this issue. SignalR seems to break when the message is over a certain size, and this issue is referenced here . To fix this, I decided to pass in the order's ID instead of the whole order object, and do another GET call to retrieve the details in a separate API call to keep the SignalR message small.