SignalR数据库改变无法在asp.net web api中工作

Question

我尝试使用signalR来获取数据库发生变化时的通知。 但不起作用但没有错误。什么是我的错误代码。看起来像On方法dependency_OnChange无法正常工作

Global.asax中的我的代码用于启动＆amp;停止SqlDependency

protected void Application_Start()
        {
            GlobalConfiguration.Configure(WebApiConfig.Register);
            //..
            SqlDependency.Start(ConfigurationManager.ConnectionStrings["SQL_ConStr"].ConnectionString);
        }
protected void Application_End()
        {
            SqlDependency.Stop(ConfigurationManager.ConnectionStrings["SQL_ConStr"].ConnectionString);
        }

这是我的班级观看有关变化的数据并获得返回数据

public DataTable DTResultOnSQLDepencyChange(string query)
        {
            Dt = new DataTable();
            if (!String.IsNullOrEmpty(query))
            {                
                OpenConn();

                cmd = new SqlCommand(query, SqlConn);
                cmd.Notification = null;
                SqlDependency dependency = new SqlDependency(cmd);
                dependency.OnChange += new OnChangeEventHandler(dependency_OnChange);
                if (SqlConn.State == ConnectionState.Closed)
                    SqlConn.Open();


                Da = new SqlDataAdapter(cmd);
                Da.Fill(Dt);

            }

            return Dt;
        }

 private void dependency_OnChange(object sender, SqlNotificationEventArgs e)
        {
            NotificationsHub.NotifyAllClients(e.Info.ToString());
        }

这是我的中心

[HubMethodName("notifyAllClients")]
        public static void NotifyAllClients(string message)
        {
            IHubContext context = GlobalHost.ConnectionManager.GetHubContext<NotificationsHub>();
            context.Clients.All.displayNotification(message);
        }

这是我的初创公司

public class Startup
    {
        public void Configuration(IAppBuilder app)
        {
            // For more information on how to configure your application, visit http://go.microsoft.com/fwlink/?LinkID=316888
            app.MapSignalR();
        }
    }

这是我的控制器

[RoutePrefix("api")]
    public class indexController : ApiController
    {
        [Route("index/{GetEvents}")]
        public List<mdEvent> getEvents()
        {
            List<mdEvent> mdEvents = new List<mdEvent>();
            string SQL = string.Format("select * from master");
            MainDB mainDB = new MainDB();
            DataTable dt = mainDB.DTResultOnSQLDepencyChange(SQL);
            if (dt.Rows.Count > 0)
            {
                foreach (DataRow dr in dt.Rows)
                {
                    mdEvent _mdEvent = new mdEvent();
                    _mdEvent.main_master_id = dr["main_master_id"].ToString();
                    _mdEvent.event_id = dr["road_map_id"].ToString();
                    _mdEvent.road_map_date = dr["road_map_date"].ToString();
                    _mdEvent.road_map_time = dr["road_map_time"].ToString();
                    _mdEvent.num_passenger = dr["num_passenger"].ToString();
                    _mdEvent.base_vehicle_id = dr["base_vehicle_id"].ToString();
                    _mdEvent.description = dr["road_map_description"].ToString();
                    _mdEvent.from_location = dr["from_location"].ToString();
                    _mdEvent.to_location = dr["to_location"].ToString();
                    _mdEvent.duration = dr["duration"].ToString();
                    _mdEvent.requestor_id = dr["requestor_id"].ToString();
                    _mdEvent.requestor_name = dr["requestor_name"].ToString();
                    _mdEvent.requestor_position_id = dr["requestor_position_id"].ToString();
                    _mdEvent.requestor_position = dr["requestor_position"].ToString();
                    _mdEvent.requestor_dept_id = dr["requestor_dept_id"].ToString();
                    _mdEvent.master_description = dr["main_master_description"].ToString();
                    _mdEvent.remark = dr["remark"].ToString();
                    _mdEvent.request_type_id = dr["request_type_id"].ToString();

                    mdEvents.Add(_mdEvent);
                }
            }

            return mdEvents;
        }
    }

这是我的观点

<script src="../Scripts/jquery.signalR-2.2.2.min.js"></script>
<script src='<%: ResolveClientUrl("~/signalr/hubs") %>'></script>
<script>
    function setupDatePicker() {

        jQuery('#txt_start_date, #txt_end_date').datetimepicker({
            format: 'Y-m-d H:i:s'
        });
    }

    $(function () {

        // Proxy created on the fly
        var notify = $.connection.notificationsHub;

        // Declare a function on the job hub so the server can invoke it
        notify.client.displayNotification = function (messages) {
            getEventsForCalendar(messages);
        };

        // Start the connection
        $.connection.hub.start();
        getEventsForCalendar();
    });

    function getEventsForCalendar(messages) {
        if ((messages !== undefined) || (messages != "")) {
            //console.log(messages)
        }
        var $tbl = $('#tblEventInfo');
        $.ajax({
            url: '../api/index/GetEvents',
            type: 'GET',
            datatype: 'json',
            success: function (data) {
                if (data.length > 0) {
                    $tbl.empty();
                    $tbl.append(' <tr><th>event_id</th><th>main_master_id</th><th>road_map_date</th><th>road_map_time</th>' +
                        '<th>num_passenger</th><th>base_vehicle_id</th><th>description</th><th>from_location</th>' +
                        '<th>to_location</th><th>duration</th><th>requestor_id</th><th>requestor_name</th>' +
                        '<th>requestor_position_id</th><th>requestor_position</th><th>requestor_dept_id</th><th>requestor_dept</th>' +
                        '<th>master_description</th><th>remark</th><th>request_type_id</th>' +
                        +'</tr>');
                    var rows = [];
                    for (var i = 0; i < data.length; i++) {
                        rows.push(' <tr><td>' + data[i].event_id + '</td><td>' + data[i].main_master_id + '</td>' +
                            '<td>' + data[i].road_map_date + '</td><td>' + data[i].road_map_time + '</td><td>' + data[i].num_passenger + '</td>' +
                            '<td>' + data[i].base_vehicle_id + '</td><td>' + data[i].description + '</td><td>' + data[i].from_location + '</td><td>' + data[i].to_location + '</td>' +
                            '<td>' + data[i].duration + '</td><td>' + data[i].requestor_id + '</td><td>' + data[i].requestor_name + '</td><td>' + data[i].requestor_position_id + '</td>' +
                            '<td>' + data[i].requestor_position + '</td><td>' + data[i].requestor_dept_id + '</td><td>' + data[i].requestor_dept + '</td><td>' + data[i].master_description + '</td>' +
                            '<td>' + data[i].remark + '</td><td>' + data[i].request_type_id + '</td>' +
                            '</tr>');
                    }
                    $tbl.append(rows.join(''));
                }
            }
        });
    }