Shared ComboBox Population and Syncing Strategy in EZLogger

Purpose

This document explains how the report type ComboBoxes in ReportWizardPanel and ReportTypeView are populated using a shared list, how the selected item is passed between the forms, and how this architecture can be reused to populate other controls like ListBoxes or additional ComboBoxes.

Summary of Behavior

• The report type list is defined once in ReportTypeHandler.GetReportTypes().
• Both ReportWizardPanel and ReportTypeView use this list to populate their ComboBoxes.
• When a user opens the ReportTypeView form, the current selection is passed to it.
• If the user changes the selection and closes the form, the new value is synced back to the main panel.

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Components and Key Logic

1. Shared Method in ReportTypeHandler.vb

Public Function GetReportTypes() As List(Of String)
    Return New List(Of String) From {
        "1370(b)(1)",
        "1372(a)(1)",
        "UNLIKELY 1370(b)(1)",
        "PPR"
    }
End Function

2. Populate ComboBox in ReportWizardPanel.xaml.vb

Private Sub ReportWizardPanel_Loaded(sender As Object, e As RoutedEventArgs) Handles Me.Loaded
    ReportTypeCbo.ItemsSource = rthandler.GetReportTypes()
End Sub

3. Open Form and Sync Selection

Private Sub ConfirmReportTypeButton_Click(sender As Object, e As RoutedEventArgs)
    Dim selectedItem = ReportTypeCbo.SelectedItem

    If selectedItem IsNot Nothing Then
        Dim currentSelection As String = selectedItem.ToString()
        Dim newSelection As String = rthandler.OnConfirmReportTypeButtonClick(currentSelection)

        If Not String.IsNullOrWhiteSpace(newSelection) AndAlso newSelection <> currentSelection Then
            ReportTypeCbo.SelectedItem = newSelection
        End If
    Else
        MessageBox.Show("Please select a report type first.", "No Selection")
    End If
End Sub

4. Update OnConfirmReportTypeButtonClick to Pass and Return Value

Public Function OnConfirmReportTypeButtonClick(reportType As String) As String
    Dim host As New ReportTypeHost()
    Dim reportTypeView = CType(host.ElementHost1.Child, ReportTypeView)
    reportTypeView.InitialSelectedReportType = reportType

    host.ShowDialog()
    Return reportTypeView.ReportTypeViewCbo.SelectedItem?.ToString()
End Function

5. Initialize ComboBox in ReportTypeView.xaml.vb

Public Property InitialSelectedReportType As String

Private Sub ReportTypeView_Loaded(sender As Object, e As RoutedEventArgs) Handles Me.Loaded
    Dim reportTypes As List(Of String) = rthandler.GetReportTypes()
    ReportTypeViewCbo.ItemsSource = reportTypes

    If Not String.IsNullOrEmpty(InitialSelectedReportType) AndAlso reportTypes.Contains(InitialSelectedReportType) Then
        ReportTypeViewCbo.SelectedItem = InitialSelectedReportType
    End If
End Sub

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How to Reuse This Pattern for Other Controls

1. Define a Shared Data Method

   • Use a List(Of String) or other appropriate type.
   • Place it in a shared handler or utility class.

2. Load the Data in Your Control

   • For WPF:

     MyComboBox.ItemsSource = SharedHandler.GetItems()
     

   • For WinForms:

     MyComboBox.Items.AddRange(SharedHandler.GetItems().ToArray())
     

3. Sync Between Forms or Views

   • Pass the selected value via a public property.
   • Use ShowDialog() to wait for the user's selection.
   • Return the selected value and update the original control.

4. Validation (Optional but Recommended)

   • Always check for Nothing or empty selection.
   • Notify users with a message box if needed.

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Benefits

• Promotes DRY (Don't Repeat Yourself) principle
• Works across WPF and WinForms
• Makes forms easier to test and maintain
• Keeps data centralized and consistent

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Future Improvements

• Convert data source to load from config file or database
• Add unit tests for shared data logic
• Create a generic ControlHelper class to load lists into any control type