CODEWITHSUNDEEP
vb.netoutlook-addin
Hayat Hasan
Hayat Hasan

Reputation: 229

How to add BackgroundWorker to VSTO ThisAddIn.vb

I'm trying to build an Outlook VSTO addin (using VB.Net) to do some time consuming data searching which is also have a Form Window of to show the current status of the task running, For this I want to use BackgroundWorker but I'm not sure how to achieve this in proper way. I tried to add a BackgroundWorker programmatically as in below code but its not working. whenever I open the Outlook in Visual Studio Debugger it straightly goes to Application is in break mode where debugger is not giving any reference to the exact error. As ThisAddIn.vb is a class file there was no drag-n-drop option to add the BackgroundWorker from visual studio Toolbox. Please help. Thanks.

Public Class ThisAddIn
    Shared WithEvents BackgroundWorker_Startup As BackgroundWorker
    Public Async Sub ThisAddIn_Startup() Handles Me.Startup
        Await Task.Delay(15000)
        AddHandler BackgroundWorker_Startup.DoWork, AddressOf BackgroundWorker_Startup_DoWork
        BackgroundWorker_Startup.RunWorkerAsync()
    End Sub

    Public Shared Sub BackgroundWorker_Startup_DoWork(sender As Object, e As DoWorkEventArgs) Handles BackgroundWorker_Startup.DoWork
        'Call a function
    End Sub

    Public Shared Sub BackgroundWorker_Startup_ProgressChanged(sender As Object, e As ProgressChangedEventArgs) Handles BackgroundWorker_Startup.ProgressChanged
        Form1.Label.Text = (CType(e.UserState, String))
    End Sub

    Public Shared Sub BackgroundWorker_Startup_RunWorkerCompleted(sender As Object, e As RunWorkerCompletedEventArgs) Handles BackgroundWorker_Startup.RunWorkerCompleted
        If (e.Error IsNot Nothing) Then
            MsgBox(e.Error.Message)
        End If
    End Sub
End Class

Upvotes: 0

Views: 385

Answers (1)

Dmitry Streblechenko
Dmitry Streblechenko

Reputation: 66276

Keep in mind that Outlook Object Model cannot be used from a thread other than the main one. Starting with Outlook 2016, it will raise an exception as soon as it detects access from a secondary thread. Your only options are Extended MAPI (C++ or Delphi) or Redemption (any language - I am its author) - its RDO family of objects can be used from a secondary thread (save the value of the Namespace.MAPIOBJECT from OOM on the main thread, create a new instance of the RDOSession object on the secondary thread, set its MAPIOBJECT property to the value saved on the main thread).

Windows controls also have thread affinity. In case of WinForms, that means you need to use Control.Invoke or Dispatcher object to make sure the code is executed on the main thread where the control was created.

Upvotes: 2

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