VB.NET: DYNAMICALLY ADD ARRAY TO COMBOBOX

Question

Does anyone know how to dynamically add an array to a bunch of comboboxes in VB.net? I could really use the help (I've been struggling with this all day). When I try to do it my way I get an error on form load.

My code:

Private Sub Form1_Load(ByVal sender as Object, ByVal e as EventArgs) Handles Me.Load
    Dim MyArray() as String = {"a","b","c"}

    For each ctl as ComboBox in Me.Controls
        if ctl.tag = "yadda" then ctl.Items.AddRange(MyArray)
    Next
End Sub

Error: "Unable to cast object of type '...Button' to type '...Combobox'."

I've tried so many variations to this code but I just can't get it to work. I will eventually have nearly a hundred similarly constructed comboboxes in my application, and I'd like to be able to programmatically initialize their items. Could someone please help?

Thanks,

Elias

spelltox · Accepted Answer · 2013-08-11 12:08:48Z

3

This is the way to do it :

Public Class Form1

    Function getControl(ByVal controlName As String) As Control
        Dim numCtrls = Me.Controls.Count()
        For I As Integer = 0 To numCtrls - 1
            If Me.Controls.Item(I).Name = controlName Then
                If TypeOf Me.Controls.Item(I) Is ComboBox Then
                    Return CType(Me.Controls(controlName), ComboBox)
                End If
            End If
        Next
    End Function

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load

        Dim myArray As Array = {"a", "b", "c"}
        Dim myComboBox As ComboBox

        For Each ctl As Control In Me.Controls
            If TypeOf ctl Is ComboBox Then
                If ctl.Tag = "yadda" Then
                    myComboBox = getControl(ctl.Name)
                    myComboBox.Items.AddRange(myArray)
                End If
            End If
        Next

    End Sub

End Class

You loop through all controls (buttons, combo, etc ...) then you check if it is the type you want (ComboBox) and do whatever you need.

Good luck !

edited Aug 11, 2013 at 12:08

answered Aug 6, 2013 at 8:45

spelltox

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4 Comments

Elias Over a year ago

Unfortunately, I get an error when I do it that way. Error: 'items' is not a member of 'System.Windows.Forms.Control'. I get blue squiggly lines beneath "ctl.items". It seems to not recognize ctl as a ComboBox. The program won't even run.

spelltox Over a year ago

@Elias my bad ... :-) you should change "If TypeOf cntrl Is" to "If TypeOf ctl Is". I've updated the code.

Elias Over a year ago

Yeah, well, that wasn't the problem. I noticed the minor typo when you originally wrote it. The problem is that VS2012 won't compile the code because it won't recognize "ctl" as a combobox. I am still experiencing this issue.

spelltox Over a year ago

@Elias Hi again, Sorry for that, my VB.Net i a little rusty ... :-) Anyways - the problem is that even though VB recognize "ctl" as a ComboBox, it doesn't get get an instance of the control itself, but a string. Please check the revised code, it works for me. If this also works for you - please mark this as "answered" so other may benefit from it. Good luck !

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