How to check empty controls within tabcontrol pages? - vb.net

Question

Some of my codes are from the answers I read here in stack-overflow, one difficulty I am facing is how to check empty controls inside Tab-control with 3 pages? I have created a function that validate if the input is empty:
VB.Net Function:
Public Shared Function ValidateInput(parent As Control)
Dim ctl As Control = Nothing
For Each ctl In parent.Controls
If TypeOf ctl Is TextBox And ctl.Text.Length = 0 Or TypeOf ctl Is ComboBox And ctl.Text.Length = 0 Then
Return ctl.Name
Exit For
'--------------------------------------------------------------------
'(1.) I want this statement to check if the control is type of Tabcontrol ang check for empty input. (I have 3 pages)
ElseIf TypeOf ctl Is TabControl Then
For Each tp As TabPage In frmClientInfo.TabControl1.TabPages
For Each ctr As Control In tp.Controls
If TypeOf ctr Is TextBox OrElse TypeOf ctr Is ComboBox Then
ctl.Name = ctr.Name
Return ctl.Name
Exit For
End If
Next
Next
'--------------------------------------------------------------------
Else
ctl = Nothing
End If
Next
Return ctl
End Function
Usage:
Dim x = Functions.ValidateInput(Me)
Dim ctrlinput As Object = Me.Controls.Find(x, True).FirstOrDefault()
If TypeOf ctrlinput Is TextBox Then
ctrlinput.focus()
ElseIf TypeOf ctrlinput Is ComboBox Then
ctrlinput.DroppedDown = True
ElseIf TypeOf ctrlinput Is TabControl Then 'If control is Tab-control
Dim y = Functions.ValidateInput(Me)
Dim xinput As Object = TabControl1.Find(y, True).FirstOrDefault()
If TypeOf xinput Is TextBox Then
xinput.focus()
ElseIf TypeOf xinput Is ComboBox Then
xinput.DroppedDown = True
End If
Else
MessageBox.Show("saveeee")
Call SaveTransaction()
End If
My condition that deals with the controls outside the tab-control works. But I cant get the controls inside the tab-control pages. I want to focus the control when the function detects an empty control inside the tab-control. Let say the empty control was detected on page 3 the system will automatically jump from page 1 to page 3 and focus the empty control. Any solution? Thanks.

Answer 1

A problem here is that a tab can have another container inside it, just like your tabcontainer contains... tabs. You can bypass this by going recursive, but then your function will return everything it finds, wherever it finds it.
Here's a recursive function which will return you a list of every textbox or combobox without text it finds where you call it:
Private Function GetEmptyControls(current As Control) As List(Of Control)
Dim list As New List(Of Control)
For Each ctrl As Control In current.Controls
If TypeOf ctrl Is ContainerControl Then
'if this control is a container, add every control this function might find inside it to your list
'this is what makes this function recursive
list.AddRange(GetEmptyControls(ctrl))
Else
'add this control if it's a textbox or combobox and there's no text
If ctrl.Text = "" AndAlso (TypeOf ctrl Is TextBox OrElse TypeOf ctrl Is ComboBox) Then
list.Add(ctrl)
End If
End If
Next
Return list
End Function
You can call it on your form or on a container inside your form, or adapt it to suit your needs. Have fun!