Handling controls in nested group box.

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I am VB6 developer. Now switch to vb.net. in one situation i feel strange behavior of vb.net
I have group box in group box when i count controls on form by :
Me.controls.count then it returns only one

i have group box with 5 text box + 5 labels (main group box)
then 1 more group box inside main group box named btnFrame(group box for buttons) which have 3 buttons. so total about 15 controls on form.

for same code vb6 returns 15
and vb.net-17 returns 1 only

Basic question is how to iterate using for each loop for all controls?

What I have tried:

i tried
1-me.controls.count but failed.it returns only 1 ( i cannot loop then)
2-then i looped for each ctrl as control in me.controls. also that does not worked.

Posted 22-Aug-20 21:12pm

hemendrapadia

Updated 22-Aug-20 21:29pm

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OriginalGriff · Answer 1 · 2020-08-22T21:30:00

Solution 1

Me.Controls returns the collection for the Form - i.e. the "outer" GroupBox.
To access the inner group box, you should iterate that collection, and then it's sub-collections:

VB

For Each cOuter As Control In Me.Controls

    If cOuter.HasChildren Then

        For Each cInner As Control In cOuter.Controls

            If cInner.HasChildren Then

                For Each c As Control In cInner.Controls
                    ProcessYourControl(c)
                Next
            End If

            ProcessYourControl(cInner)
        Next
    End If

    ProcessYourControl(cOuter)
Next

The other solution is to write a recursive method that takes a Controls collection as a parameter, and processes all controls within it:

VB

Private Sub FindControls(ByVal controls As ControlCollection)
    For Each c As Control In controls

        If c.HasChildren Then
            FindControls(c.Controls)
        End If

        ProcessYourControl(c)
    Next
End Sub

And then pass that Me.Controls when you call it.

Posted 22-Aug-20 21:30pm

OriginalGriff

Comments

hemendrapadia 28-Aug-20 12:17pm

Yes i tried that recursive but it throws error.
My code is as below:

Sub ManageControlFocusColor(ByVal controls As ControlCollection)

For Each c As Control In controls

If c.HasChildren Then
ManageControlFocusColor(c.Controls) 'Throws error here
End If

If TypeOf c Is TextBox Then
If c Is ActiveControl Then
c.BackColor = Color.LightSteelBlue
Else
c.BackColor = Color.White
End If
End If
'
If TypeOf c Is Button Then
If c Is ActiveControl Then
c.BackColor = Color.LightSteelBlue
Else
c.BackColor = Button.DefaultBackColor
End If
End If
Next
End Sub
----------------------------
Error
----------------------------
System.InvalidCastException: '[A]ControlCollection cannot be cast to [B]ControlCollection. Type A originates from 'System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' in the context 'Default' at location 'C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System.Windows.Forms\v4.0_4.0.0.0__b77a5c561934e089\System.Windows.Forms.dll'. Type B originates from 'System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' in the context 'Default' at location 'C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System.Windows.Forms\v4.0_4.0.0.0__b77a5c561934e089\System.Windows.Forms.dll'.'

hemendrapadia 28-Aug-20 12:26pm

But first one is working.

hemendrapadia 29-Aug-20 1:59am

Sorry, forgot to thank you.
Thank you very much for your response.