我非常接近使用信号器创建推送通知系统，但在某处失败，请协助

Question

我想创建一个应用程序，可以在数据库中插入/更新或删除任何内容时通知用户。

我已经将 Signalr 与 sql 依赖项一起使用，但在数据库中发生更改时仍然没有收到任何通知。

这是控制器：

public class HomeController : Controller
{
public ActionResult Index()
{
return View();
}
public JsonResult GetNotificationContacts()
{
var notificationRegisterTime = Session["LastUpdated"] != null ? Convert.ToDateTime(Session["LastUpdated"]) : DateTime.Now;
NotificationComponent NC = new NotificationComponent();
var list = NC.GetContacts(notificationRegisterTime);
//update session here for get only new added contacts (notification)
Session["LastUpdate"] = DateTime.Now;
return new JsonResult { Data = list, JsonRequestBehavior = JsonRequestBehavior.AllowGet };
}
}

这就是创业公司。Cs 类

namespace PushNotification
{
public class Startup
{
public void Configuration(IAppBuilder app)
{
app.MapSignalR();
}
}
}

这是 web.config 文件中的连接字符串

<connectionStrings>
<add name="sqlConString" connectionString="data source=SHOAIBSQLEXPRESS;initial catalog=MyPushNotification;integrated security=True;" />
<add name="MyPushNotificationEntities2" connectionString="metadata=res://*/MyPushNotificationModel.csdl|res://*/MyPushNotificationModel.ssdl|res://*/MyPushNotificationModel.msl;provider=System.Data.SqlClient;provider connection string=&quot;data source=shoaibsqlexpress;initial catalog=MyPushNotification;integrated security=True;MultipleActiveResultSets=True;App=EntityFramework&quot;" providerName="System.Data.EntityClient" />
</connectionStrings>

这是我的应用程序中名为通知中心的中心

namespace PushNotification
{
public class NotificationHub : Hub
{
//public void Hello()
//{
//    Clients.All.hello();
//}
}
}

这是通知组件类

namespace PushNotification
{
public class NotificationComponent
{
//Here we will add a function for register notification (will add sql dependency)
public void RegisterNotification(DateTime currentTime)
{
string conStr = ConfigurationManager.ConnectionStrings["sqlConString"].ConnectionString;
string sqlCommand = @"SELECT [ContactId],[ContactName],[ContactNo] from [dbo].[Contacts] where [AddedOn] > @AddedOn";
//you can notice here I have added table name like this [dbo].[Contacts] with [dbo], its mendatory when you use Sql Dependency
using (SqlConnection con = new SqlConnection(conStr))
{
SqlCommand cmd = new SqlCommand(sqlCommand, con);
cmd.Parameters.AddWithValue("@AddedOn", currentTime);
if (con.State != System.Data.ConnectionState.Open)
{
con.Open();
}
cmd.Notification = null;
SqlDependency sqlDep = new SqlDependency(cmd);
sqlDep.OnChange += sqlDep_OnChange;
//we must have to execute the command here
using (SqlDataReader reader = cmd.ExecuteReader())
{
// nothing need to add here now
}
}
}
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<Contact> GetContacts(DateTime afterDate)
{
using (MyPushNotificationEntities2 dc = new MyPushNotificationEntities2())
{
return dc.Contacts.Where(a => a.AddedOn > afterDate).OrderByDescending(a => a.AddedOn).ToList();
}
}
}
}

我在global.asax文件中进行了如下更改

namespace PushNotification
{
public class MvcApplication : System.Web.HttpApplication
{
string con = ConfigurationManager.ConnectionStrings["sqlConString"].ConnectionString;
protected void Application_Start()
{
AreaRegistration.RegisterAllAreas();
RouteConfig.RegisterRoutes(RouteTable.Routes);
//here in Application Start we will start Sql Dependency
SqlDependency.Start(con);
}
protected void Session_Start(object sender, EventArgs e)
{
NotificationComponent NC = new NotificationComponent();
var currentTime = DateTime.Now;
HttpContext.Current.Session["LastUpdated"] = currentTime;
NC.RegisterNotification(currentTime);
}
protected void Application_End()
{
//here we will stop Sql Dependency
SqlDependency.Stop(con);
}
}
}

最后，这是_layout文件以及更改

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>@ViewBag.Title - My ASP.NET Application</title>
<link href="~/Content/Site.css" rel="stylesheet" type="text/css" />
<link href="~/Content/bootstrap.min.css" rel="stylesheet" />
<script src="~/Scripts/modernizr-2.6.2.js"></script>
</head>
<body>
<div class="navbar navbar-inverse navbar-fixed-top">
<div class="container">
<div class="navbar-header">  
<span class="noti glyphicon glyphicon-bell"><span class="count">&nbsp;</span></span>            
<div class="noti-content">
<div class="noti-top-arrow"></div>
<ul id="notiContent"></ul>
</div>
<button type="button" class="navbar-toggle" data-toggle="collapse" data-target=".navbar-collapse">
<span class="icon-bar"></span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
</button>
@Html.ActionLink("Application name", "Index", "Home", null, new { @class = "navbar-brand" })
</div>
<div class="navbar-collapse collapse">
<ul class="nav navbar-nav">
</ul>
</div>
</div>
</div>
<div class="container body-content">
@RenderBody()
<hr />
<footer>
<p>&copy; @DateTime.Now.Year - My ASP.NET Application</p>
</footer>
</div>
@* Add Jquery Library *@
<script src="~/Scripts/jquery-2.2.3.min.js"></script>
<script src="~/Scripts/jquery.signalR-2.2.0.min.js"></script>
<script src="/signalr/hubs"></script>
<script src="~/Scripts/bootstrap.min.js"></script>
@* Add css  *@
<link href="~/Content/bootstrap.min.css" rel="stylesheet" />
<style type="text/css">
/*Added css for design notification area, you can design by your self*/
/* COPY css content from youtube video description*/
.noti-content{
position:fixed;
right:100px;
background:#e5e5e5;
border-radius:4px;
top:47px;
width:250px;
display:none;
border: 1px solid #9E988B;
}
ul#notiContent{
max-height:200px;
overflow:auto;
padding:0px;
margin:0px;
padding-left:20px;
}
ul#notiContent li {
margin:3px;
padding:6px;
background:#fff;
}
.noti-top-arrow{
border-color:transparent;
border-bottom-color:#F5DEB3;
border-style:dashed dashed solid;
border-width: 0 8.5px 8.5px;
position:absolute;
right:32px;
top:-8px;
}
span.noti{
color:#FF2323;
margin:15px;
position:fixed;
right:100px;
font-size:18px;
cursor:pointer;
}
span.count{
position:relative;
top:-3px;
}
</style>
@* Add jquery code for Get Notification & setup signalr *@
<script type="text/javascript">
$(function () {
// Click on notification icon for show notification
$('span.noti').click(function (e) {
e.stopPropagation();
$('.noti-content').show();
var count = 0;
count = parseInt($('span.count').html()) || 0;
//only load notification if not already loaded
if (count > 0) {
updateNotification();
}
$('span.count', this).html('&nbsp;');
})
// hide notifications
$('html').click(function () {
$('.noti-content').hide();
})
// update notification 
function updateNotification() {
$('#notiContent').empty();
$('#notiContent').append($('<li>Loading...</li>'));
$.ajax({
type: 'GET',
url: '/home/GetNotificationContacts',
success: function (response) {
$('#notiContent').empty();
if (response.length  == 0) {
$('#notiContent').append($('<li>No data available</li>'));
}
$.each(response, function (index, value) {
$('#notiContent').append($('<li>New contact : ' + value.ContactName + ' (' + value.ContactNo + ') added</li>'));
});
},
error: function (error) {
console.log(error);
}
})
}
// update notification count
function updateNotificationCount() {
var count = 0;
count = parseInt($('span.count').html()) || 0;
count++;
$('span.count').html(count);
}
// signalr js code for start hub and send receive notification
var notificationHub = $.connection.notificationHub;
$.connection.hub.start().done(function () {
console.log('Notification hub started');
});
//signalr method for push server message to client
notificationHub.client.notify = function (message) {
if (message && message.toLowerCase() == "added") {
updateNotificationCount();
}
}
})
</script>
</body>
</html>

我的数据库在 sql Server 管理工作室中，当我插入新记录时，我在前端没有收到任何通知。

如果您有这方面的专业知识，请提供帮助。 提前非常感谢。

Answer 1

你必须打开服务代理

ALTER DATABASE [yourdatabasename] SET ENABLE_BROKER WITH ROLLBACK IMMEDIATE ;