SignalR SqlDependancy OnChange事件未触发

问题描述

我将SignalR与MVC一起使用，并在sqlDependency的Change Event上创建。但是当我在数据库中更新时它不会触发。当我在Db中执行查询“ ALTER DATABASE MyDatabase SET ENABLE_broKER”

我在NotificationComponent中写过

    public void RegisterNotification(DateTime currentTime)
    {
        string conStr = ConfigurationManager.ConnectionStrings["sqlConString"].ConnectionString;
        string sqlCommand = @"SELECT * from [dbo].[Event] where UpdatedTime > @UpdatedTime";
        sqlDependency.Start(conStr);

        using (sqlConnection con = new sqlConnection(conStr))
        {
            if (con.State != System.Data.ConnectionState.Open)
            {
                con.open();
            }

            sqlCommand cmd = new sqlCommand(sqlCommand,con);
            cmd.Parameters.AddWithValue("@UpdatedTime",currentTime);

            cmd.Notification = null;
            sqlDependency sqlDep = new sqlDependency(cmd);

            //sqlDep.OnChange += new OnChangeEventHandler(sqlDep_OnChange);
            sqlDep.OnChange += sqlDep_OnChange;
            //we must have to execute the command here
            
            cmd.ExecuteReader().dispose();
            //using (sqlDataReader reader = cmd.ExecuteReader())
            //{
            //    // nothing need to add here Now
            //}

        }
    }

    public void sqlDep_OnChange(object sender,sqlNotificationEventArgs e)
    {
        if (e.Type == sqlNotificationType.Change)
        {
            sqlDependency sqlDep = sender as sqlDependency;
            sqlDep.OnChange -= sqlDep_OnChange;

            //from here we will send notification message to client
            var notificationHub = GlobalHost.ConnectionManager.GetHubContext<NotificationHub>();
            notificationHub.Clients.All.notify("added");
            
            //re-register notification
            RegisterNotification(DateTime.Now);
        }
    }

    public List<Event> GetEvents(DateTime afterDate)
    {
        using (MyDatabaseEntities dc = new MyDatabaseEntities())
        {
            return dc.Events.Where(a => a.UpdatedTime > afterDate).OrderByDescending(a => a.UpdatedTime).ToList();
        }
    }

在JS中

        var notificationHub = $.connection.notificationHub;
       
       

        $.connection.hub.start().done(function () {
            console.log('Notification hub started');
        });

         notificationHub.client.notify = function (message) {
            if (message && message.toLowerCase() == "added") {
                updateNotificationCount();
            }
        }

在Startup.cs配置功能中：

app.MapSignalR（）;

解决方法

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