PASSING VALUES FROM THE VIEW TO THE HANDLER

In ReportTypeView, we retrieve the selected value from the ComboBox (ReportTypeCbo) directly in the view's code behind and pass it into the handler, rather than having the handler pull data from the UI.

This pattern is intentional and follows a key design principle:

"Handlers should not reach into views to get control values."

Instead the view is responsible for reading the control state (such as SelectedItem or SelectedDate) and sending those values as arguments when calling into the handler.

Example

' Example from ReportTypeView.xaml.vb

Private Sub ReportTypeSelectedBtn_Click(sender As Object, e As RoutedEventArgs)
		Dim selectedReportType As String = TryCast(ReportTypeCbo.SelectedItem, String)
		Dim selectedReportDate As String = GetSelectedReportDate()
		_handler.ReportTypeSelectedBtnClick(selectedReportType, selectedReportDate, _hostForm)
End Sub

This ensures that:

• Views handle UI concerns (e.g., getting selected ComboBox items)
• Handlers stay clean and focused on processing logic, using only the data passed to them
• Tight coupling between UI controls and logic layers is avoided

It's a good practice for keeping views and handlers decoupled, maintainable, and testable.