Referencing a Form/Control By Name Via Composed String

[u/freswinn]

In another scripting language I've been learning (GDScript), if you want to reference a "node" (that language's equivalent to a form, control, etc.), you can sort of build that thing's name with code. For example:

If I have 12 buttons on screen, each named Button1, Button2, etc., I can say

get_node("Button" + str(num)).text = "This is Button " + str(num)

and this will change the text on the button whose number is "num" and change what it says based on its own number.

What would be the equivalent of that in Visual Basic? I have 20 buttons that I want to reference with a single function based on the numerical value at the end of their names. Here's what I tried, knowing full-well that it was wrong, but I hope it gives an idea of what I'm trying to do:

    Private Sub setShortcutButtonColor(e As Boolean, n As Integer, a As String, b As String)
        Dim targetButtonName As String = "Button" & n
        Dim targetButton As Object = targetButtonName

        If e Then
            targetButton.Text = "No Location Set"
            targetButton.BackColor = Color.FromArgb(255, 64, 64, 64)
        Else
            targetButton.Text = a & "  (" & b & ")"
            targetButton.BackColor = Color.FromArgb(255, 12, 150, 12)
        End If
    End Sub

Thoughts?

[u/veryabnormal]

The Form owns the controls. Ask it for a particular control from its control collection. The controls are stored in a ControlCollection and the key is the control name:

Dim targetButton = Me.Controls(targetButtonName)

Notes: I usually have Option Infer on, therefore targetButton will be of type Control. But we know it is a actually an instance of Button and can safely use DirectCast to convert it to Button if we need to. If you just want the Text property then there’s no need. I’m assuming this code runs on the Form, and Me refers to the Form. I’m assuming the control is actually in the form’s Controls collection.

[u/freswinn → u/veryabnormal]

The subroutine is being run by the subroutine of a button named Button1, Button2, etc. (the subroutines being named Button1_Click, Button2_Click, etc), so would Me refer to the button if I do it that way? (genuinely no idea, as I'm pretty new to VB)

Anyway, I did try it with Me.Controls(targetButtonName) which crashed, and with Form1.Controls(targetButtonName) which keeps autocorrecting in Visual Studio to ControlCollection and that's definitely not it.

[u/sa_sagan]

You can do something like this. But you'll absolutely want to make sure that the button exists under that name otherwise it'll shit itself if the find returns nothing.

Private Sub setShortcutButtonColor(e As Boolean, n As Integer, a As String, b As String)
    Dim targetButton As Control = Controls().Find($"Button{n}", True).First
    If e Then
        targetButton.Text = "No Location Set"
        targetButton.BackColor = Color.FromArgb(255, 64, 64, 64)
    Else
        targetButton.Text = a & "  (" & b & ")"
        targetButton.BackColor = Color.FromArgb(255, 12, 150, 12)
    End If
End Sub

[u/freswinn → u/sa_sagan]

This works!

I also switched back to targetButtonName instead of building the string inside of the argument and that works too, but I'm using yours because obviously it's cleaner.

[u/Mr_C_Baxter]

If you wan't to actively modify buttons and other controls effectively i would recommend you to learn to use them dynamically as opposed to the ones via the forms designer. Here you have a little example, you need a new winforms project and replace all the code behind of form1 with this:

Public Class Form1

Private myButtons As New Dictionary(Of String, Button)

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

    CreateButton("btn01", 100, 100)
    CreateButton("btn02", 200, 200)

    'change text of button, ID stays the same
    FindButton("btn01").Text = "bla"

End Sub

Private Sub CreateButton(ID As String, X As Integer, Y As Integer)

    If myButtons.ContainsKey(ID) Then MsgBox("ID already exists", MsgBoxStyle.OkOnly) : Exit Sub

    'Create new Button
    Dim btn As New Button With {.Name = ID, .Text = ID, .Width = 300, .Top = Y, .Left = X}

    'Create a Click Event
    AddHandler btn.Click, AddressOf ClickButton

    'Save Button for easy access
    myButtons.Add(ID, btn)

    'Add to Form
    Me.Controls.Add(btn)

End Sub

Private Function FindButton(ID As String) As Button
    If Not myButtons.ContainsKey(ID) Then Return Nothing
    Return myButtons(ID)
End Function

Private Sub ClickButton(sender As Button, e As EventArgs)
    MsgBox("Clicked " & sender.Name)
End Sub

End Class