Question

I have the following lines of code as a test user control. When the project is built, and I drag this user control onto a form, I get an error dialogue to the effect that EF can’t find the connection string for the context. Yet when I use the same variable in a form, all is well. It seems the user control is using a different context within which to look for the connection string than the usual app.config.

Public Class InvoiceWorkOrderSearch
    Private _dataHelper As WorkOrderData = New WorkOrderData()
End Class

Answer 1

During Design time?

You can avoid this be only instancing the object if the control is in runtime mode.

The build in property to check for desing time (Me.DesignMode) is poor since it only tells you if you are currently designing the control itself. It returs false if you drop the usercontrol on a form.

You can use this code to check for designtime: http://dotnet-snippets.de/dns/designmode-workaround-windows-forms-SID299.aspx

Public Class InvoiceWorkOrderSearch
    Private _dataHelper As WorkOrderData

    Public Sub New()
        If IsDesignMode(me) = False Then
            _dataHelper = New WorkOrderData()
        End If
    End Sub()
End Class