Tracking number of open raddesktop alerts

[John]

Hi I want to show only upto 3 desktop alerts at any given time.  Some alerts have autoclose options while others do not.  As such before displaying an alert, I need to check how many are open.  I tried using the desktopalertmanager but running into null exception errors

Dim

 

iDesktopAlertManager As DesktopAlertManager
Dim value As IEnumerator(Of RadDesktopAlert)
value = iDesktopAlertManager.GetRegisteredAlerts()

 

I stepped though the code and the iDesktopAlertManager is nothing which causes a null exception error.  I am not fully aware of the DesktopAlertManager.

This is similar to the code sample on your reference pages so not sure what I am doing wrong here...
http://www.telerik.com/help/winforms/telerik.wincontrols.ui-telerik.wincontrols.ui.desktopalertmanager-getregisteredalerts.html

[Richard Slade]

Hello John,

Please can you try this in a new project. It's just a form and a RadButton

Private m_Alerts As New List(Of Telerik.WinControls.UI.RadDesktopAlert)
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
End Sub
Private Sub Alert_Closed(ByVal Sender As Object, ByVal e As EventArgs)
    m_Alerts.Remove(CType(Sender, Telerik.WinControls.UI.RadDesktopAlert))
End Sub
Private Sub ButtonGenerateAlert_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ButtonGenerateAlert.Click
    If m_Alerts.Count < 3 Then
        Dim alert As New Telerik.WinControls.UI.RadDesktopAlert()
        alert.CaptionText = "Alert Header"
        alert.ContentText = "Alert Context"
        m_Alerts.Add(alert)
        alert.Show()
        AddHandler alert.Closed, AddressOf Alert_Closed
    End If
End Sub

Hope that helps
Richard

[Richard Slade]

Hello,

Did this help? If so please remember to mark as answer. If you need morre assistance just let me know.
Regards,
Richard

[Ivan Todorov]

Hello John,

Here is the proper way to use the DesktopAlertManager to get the count of the shown alerts:

Public Function GetAlertCount() As Integer
    Dim count As Integer = 0
    Dim alerts As IEnumerator(Of RadDesktopAlert) = DesktopAlertManager.Instance.GetRegisteredAlerts()
    While alerts.MoveNext()
        count += 1
    End While

    Return count
End Function

Richard's approach could also do the required task.

I hope this was helpful. Should you have any further questions, do not hesitate to ask.

Greetings,
Ivan Todorov
the Telerik team

[John]

I will try this option and update with my findings.

[Ivan Todorov]

Hi John,

Please let us know if this worked for you, when you try it. I will be glad to assist you if you need further help, so do not hesitate to write back.

Greetings,

Ivan Todorov

the Telerik team