CODEWITHSUNDEEP
powershell
Wakan Tanka
Wakan Tanka

Reputation: 8042

winforms change button name depending on label

My goal is to change button text depending on text which is displayed by Label. I have following code:

Add-Type -AssemblyName System.Windows.Forms

class MyForm : System.Windows.Forms.Form {
    MyForm($mystuff) {
        #Do-Stuff
        $this.Add_Load( $this.MyForm_Load )
    }

    $MyForm_Load = {

        $mlabel = [System.Windows.Forms.Label]::new()
        $mlabel.Name = "status"
        $mlabel.Text = "enabled"


        $mbutton = [System.Windows.Forms.Button]::new()
        if ($this.parent.controls["status"].text -eq "enabled"){
            $mbutton.text = "disable"
        }else{
            $mbutton.text = "enable"
        }

        $mbutton.Location = [System.Drawing.Point]::new(100,100)
        $mbutton.Add_Click( $this.mbutton_click )

        $this.Controls.Add($mlabel)
        $this.Controls.Add($mbutton)
    }

    $mbutton_click = {
        if ($this.Parent.Controls["status"].Text -eq "enabled"){
            $this.Parent.Controls["status"].Text = "disabled"
        }
        else{
            $this.Parent.Controls["status"].Text = "enabled"
        }
    }
}

$foo = [MyForm]::new("test")
$foo.ShowDialog()

But this script returns me following error:

Cannot index into a null array.
At C:\Users\wakatana\Desktop\toggle_button_name\forms2.ps1:50 char:13
+         if ($this.parent.controls["status"].text -eq "enabled"){
+             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: (:) [], RuntimeException
    + FullyQualifiedErrorId : NullArray

EDIT - Final working solution:

Add-Type -AssemblyName System.Windows.Forms

class MyForm : System.Windows.Forms.Form {
    MyForm($mystuff) {
        #Do-Stuff
        $this.Add_Load( $this.MyForm_Load )
    }

    $MyForm_Load = {
        $mlabel = [System.Windows.Forms.Label]::new()
            $mlabel.Name = "label"
            $mlabel.Text = "disabled"

        $mbutton = [System.Windows.Forms.Button]::new()
            $mbutton.Name = "button"
            $mbutton.Location = [System.Drawing.Point]::new(100,100)
            $mbutton.Add_Click( $this.mbutton_click )

        $this.Controls.Add($mlabel)
        $this.Controls.Add($mbutton)

    # ----------------------------------------------
    # Now $this.controls has something. We can now access it.
    # ----------------------------------------------
        if ($this.controls["label"].text -eq "enabled"){
            $mbutton.text = "disable"
        }else{
            $mbutton.text = "enable"
        }
    }

    $mbutton_click = {
        if ($this.Parent.Controls["label"].Text -eq "enabled"){
            $this.Parent.Controls["label"].Text = "disabled"
            $this.Parent.Controls["button"].Text = "enable"
        }
        else{
            $this.Parent.Controls["label"].Text = "enabled"
            $this.Parent.Controls["button"].Text = "disable"
        }
    }
}

$foo = [MyForm]::new("test")
$foo.ShowDialog()

Upvotes: 0

Views: 42

Answers (1)

HAL9256
HAL9256

Reputation: 13463

Edit:

$this.parent.controls is empty for 2 reasons.

  1. Because you have not added anything to the form yet.
  2. Because you are inside $MyForm_Load, there is no need for $this.parent as you are the parent. Simply remove the .parent and access the controls directly.

E.g. Trying to access something that is empty throws the error:

$MyForm_Load = {
    $mlabel = [System.Windows.Forms.Label]::new()
    $mlabel.Name = "status"
    $mlabel.Text = "enabled"

    $mbutton = [System.Windows.Forms.Button]::new()

# ----------------------------------------------
# Here - $this.controls is empty trying to access will throw error
# ----------------------------------------------

    if ($this.controls["status"].text -eq "enabled"){
        $mbutton.text = "disable"
    }else{
        $mbutton.text = "enable"
    }

    $mbutton.Location = [System.Drawing.Point]::new(100,100)
    $mbutton.Add_Click( $this.mbutton_click )

# ----------------------------------------------
# Here - this.controls is still empty
# ----------------------------------------------

    $this.Controls.Add($mlabel)
    $this.Controls.Add($mbutton)

# ----------------------------------------------
# Now $this.controls has something.
# ----------------------------------------------

}

So by rearranging your script to access the control after you have Added it, and by referencing $this.controls, you get:

$MyForm_Load = {
    $mlabel = [System.Windows.Forms.Label]::new()
    $mlabel.Name = "status"
    $mlabel.Text = "enabled"

    $mbutton = [System.Windows.Forms.Button]::new()

    $mbutton.Location = [System.Drawing.Point]::new(100,100)
    $mbutton.Add_Click( $this.mbutton_click )

    $this.Controls.Add($mlabel)
    $this.Controls.Add($mbutton)

# ----------------------------------------------
# Now $this.controls has something. We can now access it.
# ----------------------------------------------

    if ($this.controls["status"].text -eq "enabled"){
        $mbutton.text = "disable"
    }else{
        $mbutton.text = "enable"
    }
}

Upvotes: 1

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