我是第一次实现 signalR 概念，它在第一次加载页面时工作，当我对数据库执行任何插入、删除或更新操作时，它会调用代码中指定的方法，但我得到的是 Context 的空值.User.Identity.Name。我使用了 FormAuthentication 并在登录后获得了 connectionId 和用户名，但是在对数据库表进行更改后获得了用户名的空值。下面我提到了我的代码。
中心类
namespace SCPLTabAssessPortal
{
public class User
{
public string Name { get; set; }
public HashSet<string> ConnectionIds { get; set; }
}
[Authorize]
public class DashboardNewHub : Hub
{
int totalNewMessages = 0;
int ttltdy = 0;
int Ttlnum = 0;
int totalNewNotification = 0;
private static readonly ConcurrentDictionary<string, User> Users = new ConcurrentDictionary<string, User>();
public override Task OnConnected()
{
string userName = Context.User.Identity.Name;
string connectionId = Context.ConnectionId;
var user = Users.GetOrAdd(userName, _ => new User
{
Name = userName,
ConnectionIds = new HashSet<string>()
});
lock (user.ConnectionIds)
{
user.ConnectionIds.Add(connectionId);
Clients.AllExcept(user.ConnectionIds.ToArray()).userConnected(userName);
// TODO: Broadcast the connected user
}
return base.OnConnected();
}
public override Task OnDisconnected(bool stopCalled)
{
string name = Context.User.Identity.Name;
User rmuser;
Users.TryRemove(name, out rmuser);
return base.OnDisconnected(stopCalled);
}
public override Task OnReconnected()
{
string name = Context.User.Identity.Name;
string connectionId = Context.ConnectionId;
var user = Users.GetOrAdd(name, _ => new User
{
Name = name,
ConnectionIds = new HashSet<string>()
});
lock (user.ConnectionIds)
{
user.ConnectionIds.Add(connectionId);
Clients.AllExcept(user.ConnectionIds.ToArray()).userConnected(name);
// TODO: Broadcast the connected user
}
return base.OnReconnected();
}
[HubMethodName("sendNotifications")]
public string SendNotifications()
{
IEnumerable<string> allReceivers = null;
try
{
User getuser = GetUser(Context.User.Identity.Name);
using (var connection = new SqlConnection(ConfigurationManager.ConnectionStrings["SCPLDBPortalConnectionString"].ConnectionString))
{
string query = "SELECT [ColumnName],[ColumnName] FROM [dbo].[TableName] ";
connection.Open();
using (SqlCommand command = new SqlCommand(query, connection))
{
try
{
command.Notification = null;
DataTable dt = new DataTable();
SqlDependency dependency = new SqlDependency(command);
dependency.OnChange += new OnChangeEventHandler(dependency_OnChange);
if (connection.State == ConnectionState.Closed)
connection.Open();
var reader = command.ExecuteReader();
dt.Load(reader);
if (dt.Rows.Count > 0)
{
int totaltax = 0;
foreach (DataRow r in dt.Rows)
{
totaltax += (string.IsNullOrEmpty(Convert.ToString(r["TaxTotal"])) ? 0 : Convert.ToInt32(r["TaxTotal"]));
}
totalNewMessages = totaltax;
}
connection.Close();
}
catch (Exception ex)
{
throw;
}
}
}
User receiver;
if (Users.TryGetValue(getuser.Name, out receiver))
{
User sender = GetUser(Context.User.Identity.Name);
lock (receiver.ConnectionIds)
{
lock (sender.ConnectionIds)
{
allReceivers = receiver.ConnectionIds.Concat(sender.ConnectionIds);
}
}
foreach (var cid in allReceivers)
{
Clients.Client(cid).received(totalNewMessages);
}
}
}
catch (Exception ex) {
}
IHubContext context = GlobalHost.ConnectionManager.GetHubContext<DashboardNewHub>();
return (string)context.Clients.Client(Convert.ToString(allReceivers.Last())).RecieveNotification(totalNewMessages).Result;
}
private void dependency_OnChange(object sender, SqlNotificationEventArgs e)
{
if (e.Type == SqlNotificationType.Change)
{
DashboardNewHub nHub = new DashboardNewHub();
nHub.SendNotifications();
}
}
private User GetUser(string username)
{
User user;
Users.TryGetValue(username, out user);
return user;
}
}
}
Jquery代码
jQuery(document).ready(function () {
// Declare a proxy to reference the hub.
var notifications = $.connection.dashboardNewHub;
// Create a function that the hub can call to broadcast messages.
notifications.client.recieveNotification = function (totalNewMessages, ttltdy) {
$('#TtlColl').text(totalNewMessages);
};
// Start the connection.
$.connection.hub.start().done(function () {
notifications.server.sendNotifications();
}).fail(function (e) {
alert(e);
});
});
全局.asax.cs
protected void Application_Start(object sender, EventArgs e)
{
SqlDependency.Start(ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString);
}
protected void Application_End(object sender, EventArgs e)
{
SqlDependency.Stop(ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString);
}
登录.cs
我在用户登录时编写的以下代码。
FormsAuthentication.RedirectFromLoginPage(txtUserName.Text, true);
FormsAuthentication.SetAuthCookie(txtUserName.Text + "$" + DS.Tables[0].Rows[i]["ID"].ToString(), true);
最佳答案
关键是因为调用 nHub.SendNotifications() 的 sql broker 引擎您无法获得有关登录用户的任何信息，因为不是登录用户正在发出请求
关于c# - 在事件触发 SqlDependency 后获取 Context.User.Identity.Name Null，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/43672124/