Use Async/Await with a Custom Progress Bar in EZLogger

Overview

This article explains how I used Async/Await in VB.NET to support a background Excel lookup while displaying a custom animated progress indicator in my EZLogger project. The feature allows the program to look up a "CONREP" provider from an Excel file using a patient number, and write the result to the custom document properties of the active Word document.

Why I Needed Async/Await

During development, I discovered that calling ExcelHelper.GetProviderFromHLV(patientNumber) directly would freeze the UI and stop the animation in my BusyControl. This happened because Excel interop operations block the UI thread.

To solve this, I:

• Moved the Excel lookup to a background thread using Tasks.Task.Run
• Used Await to keep the method responsive
• Used Task.Delay to allow the UI time to render before starting the background task

What I Built

To implement this feature, I created the following components:

• BusyControl.xaml: A WPF UserControl with an indeterminate ProgressBar and lime green "Working..." text
• BusyHost.vb: A WinForms form using ElementHost to display the BusyControl
• ShowBtnEMessage: An async method inside ReportWizardHandler.vb to run the Excel lookup and update Word properties
• ExcelHelper.vb: Handles reading the HLV Excel workbook
• DocumentPropertyHelper.vb: Handles writing the result to Word custom properties

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Core Function: ShowBtnEMessage

Imports Tasks = System.Threading.Tasks

Public Async Sub ShowBtnEMessage(patientNumber As String)
    Dim provider As String = Nothing
    Dim busyForm As New BusyHost()
    busyForm.Show()

    Await Tasks.Task.Delay(100) ' Allow spinner UI to fully render

    Try
        provider = Await Tasks.Task.Run(Function()
            Return ExcelHelper.GetProviderFromHLV(patientNumber)
        End Function)
    Finally
        busyForm.Close()
    End Try

    If Not String.IsNullOrWhiteSpace(provider) Then
        DocumentPropertyHelper.WriteCustomProperty(
            Globals.ThisAddIn.Application.ActiveDocument,
            "CONREP",
            provider
        )
        MsgBoxHelper.Show($"Provider found and saved to CONREP: {provider}")
    Else
        MsgBoxHelper.Show($"No provider found for patient number: {patientNumber}")
    End If
End Sub

Why I Used Task.Delay(100)

This small delay ensures that the BusyControl renders and begins animating before Excel work begins. Without it, the form appears but remains frozen during processing.

Why I Used Task.Run

ExcelHelper.GetProviderFromHLV performs blocking Excel interop. By using Task.Run, I ensured that the long-running task executes on a background thread, allowing the UI to remain responsive.

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Trigger: Btn_E_Click

The process starts in Btn_E_Click within ReportWizardPanel.xaml.vb. Here's how I connected the trigger to the async logic:

Private Sub Btn_E_Click(sender As Object, e As RoutedEventArgs)
    TaskPaneHelper.SetTaskPane(Me)

    Dim patientNumber As String = TextBoxPatientNumber.Text?.Trim()

    If String.IsNullOrWhiteSpace(patientNumber) Then
        MsgBoxHelper.Show("No patient number found. Please return to Step A to complete this information.")
        Exit Sub
    End If

    _handler.ShowBtnEMessage(patientNumber)
    TimerHelper.DisableTemporarily(Btn_E, 2000)
End Sub

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Summary

This pattern allows my EZLogger UI to remain responsive while running Excel lookups in the background. It uses Async/Await in VB.NET, together with a custom progress form, to create a smoother user experience.

Reuse

I plan to reuse this pattern in future tasks like:

• Exporting to PDF
• Long-running merges
• SharePoint uploads
• Excel reads or SQL queries

It’s now my go-to structure for any operation that should not block the UI.