SignalR 客户端不会打印队列位置

Question

我的 SignalR 客户端有以下代码。根据我到目前为止的知识，这段代码应该打印“noitfyQueuePosition”事件发送的任何内容。

using Microsoft.AspNetCore.SignalR.Client;

Console.WriteLine("Connecting to Hub...");

var hubConnection = new HubConnectionBuilder().WithUrl("https://localhost:7178/queueHub").Build();

hubConnection.Closed += async (error) =>
{
    Console.WriteLine("Connection closed. Reconnecting...");
    await Task.Delay(new Random().Next(0, 5) * 1000);
    await hubConnection.StartAsync();
};

hubConnection.On<string>("notifyQueuePosition", (queueCount) =>
{
    Console.WriteLine($"Message received from server: {queueCount}");
});

try
{
    await hubConnection.StartAsync();
    Console.WriteLine("Connected to SignalR Hub.");

    await hubConnection.InvokeAsync("JoinQueue", "fj294ij29r8jv09258jwr0fj2508f2trvjh2");
}
catch (Exception ex)
{
    Console.WriteLine($"Error connecting to SignalR Hub: {ex.Message}");
}

Console.ReadLine();

我在另一个类中使用集线器的实例，并使用以下方法将队列计数发送到服务器中的每个连接。 “等待_queueHub.Clients.All.SendAsync（“notifyQueuePosition”，queueCount）;“

问题是队列计数没有打印在我的客户控制台上。

Answer 1

我创建了一个后台服务并重现了您的问题，我收到如下错误。错误可能与您这边相同，如果不是，请检查下面的建议，它可以帮助您打印更多详细信息，例如我的图片。

然后我添加

Newtonsoft.Json

包并格式化数据，然后解决问题。

像下面这样

public Task AddToQueue(string userToken)
{
    _queueManager.JoinQueue(userToken, Context.ConnectionId);
    // using JsonConvert.SerializeObject to format the data
    Clients.All.SendAsync("notifyQueuePosition", JsonConvert.SerializeObject(1));
    return Task.CompletedTask;
}

// the method inside my test service
private void OnNotifyQueuePositionHandler(string queueCount)
{
    var data = JsonConvert.DeserializeObject(queueCount);
    Console.WriteLine($"Message received from server: {queueCount}");
}

这是我的完整代码。

using WebApplication2.IServices;
using Microsoft.AspNetCore.SignalR.Client;
using Newtonsoft.Json;

namespace WebApplication2.BackgroundServices
{
    public class HubClientService : BackgroundService
    {
        private readonly IQueueManager _queueManager;

        public HubClientService(IQueueManager queueManager)
        {
            _queueManager = queueManager;
        }

        protected override async Task ExecuteAsync(CancellationToken stoppingToken)
        {
            while (!stoppingToken.IsCancellationRequested)
            {
                //Console.WriteLine(DateTime.UtcNow.ToString("yyyy-MM-dd HH:mm:ss") + $"   The number of members in the queue: {_queueManager?.UserQueue?.Count}");
                //await Task.Delay(5000, stoppingToken);
                Console.WriteLine("Connecting to Hub...");

                var hubConnection = new HubConnectionBuilder().WithUrl("https://localhost:7245/queueHub").ConfigureLogging(logging =>
                {
                    // Log to the Console
                    logging.AddConsole();

                    // This will set ALL logging to Debug level
                    logging.SetMinimumLevel(LogLevel.Debug);
                }).Build();

                hubConnection.Closed += async (error) =>
                {
                    Console.WriteLine("Connection closed. Reconnecting...");
                    await Task.Delay(new Random().Next(0, 5) * 1000);
                    await hubConnection.StartAsync();
                };

                //hubConnection.On<string>("notifyQueuePosition", (queueCount) =>
                //{
                //  Console.WriteLine($"Message received from server: {queueCount}");
                //});

                hubConnection.On<string>("notifyQueuePosition", OnNotifyQueuePositionHandler);


                try
                {
                    await hubConnection.StartAsync();
                    Console.WriteLine("Connected to SignalR Hub.");

                    await hubConnection.InvokeAsync("AddToQueue", "fj294ij29r8jv09258jwr0fj2508f2trvjh2");
                }
                catch (Exception ex)
                {
                    Console.WriteLine($"Error connecting to SignalR Hub: {ex.Message}");
                }

                await Task.Delay(5000, stoppingToken);
            }
        }
        public Func<string, Task>? NotifyQueuePositionHandler { get; set; }
        private void OnNotifyQueuePositionHandler(string queueCount)  
        {
            var data = JsonConvert.DeserializeObject(queueCount);
            Console.WriteLine($"Message received from server: {queueCount}");
        }
    }
}

建议

我们需要启用信号器客户端日志记录以检查详细消息。

var connection = new HubConnectionBuilder()
.WithUrl("https://example.com/my/hub/url")
.ConfigureLogging(logging =>
{
    // Log to the Console
    logging.AddConsole();

    // This will set ALL logging to Debug level
    logging.SetMinimumLevel(LogLevel.Debug);
})
.Build();