How to update or refresh comboBox item with button.add_click function in PowerShell?

Question

I use a ComboBox to get a directory. I need to update the directory by using the Button.Click event.

Add-Type -AssemblyName System.Windows.Forms
[System.Windows.Forms.Application]::EnableVisualStyles()

$Form                            = New-Object system.Windows.Forms.Form
$Form.ClientSize                 = '400,400'
$Form.TopMost                    = $false

$ComboBox1                       = New-Object system.Windows.Forms.ComboBox
$ComboBox1.width                 = 100
$ComboBox1.height                = 20
$ComboBox1.location              = New-Object System.Drawing.Point(36,60)
$ComboBox1.Font                  = 'Microsoft Sans Serif,10'
$list = @(Get-ChildItem -Directory ".\").Name
foreach ($lst in $list) {
    $ComboBox1.Items.Add($lst)
}
$Button1                         = New-Object system.Windows.Forms.Button
$Button1.text                    = "update"
$Button1.width                   = 60
$Button1.height                  = 30
$Button1.location                = New-Object System.Drawing.Point(182,60)
$Button1.Font                    = 'Microsoft Sans Serif,10'
$Button1.Add_Click({
})

$Form.controls.AddRange(@($ComboBox1,$Button1))
$Form.ShowDialog()

Answer 1

You are populating the ComboBox with this...

$list = @(Get-ChildItem -Directory ".\").Name
foreach ($lst in $list) {
    $ComboBox1.Items.Add($lst)
}

It sounds like you want clicking the Button to simply do that again so the ComboBox will contain an up-to-date list of directories. In that case your Click event handler should be created like this...

$Button1.Add_Click({
    # Remove all items from the ComboBox
    $ComboBox1.Items.Clear()

    # Repopulate the ComboBox, just like when it was created
    $list = @(Get-ChildItem -Directory ".\").Name
    foreach ($lst in $list) {
        $ComboBox1.Items.Add($lst)
    }
})

Clear() is called first so you don't end up with duplicate directory items.

By the way, you can simplify this...

$list = @(Get-ChildItem -Directory ".\").Name
foreach ($lst in $list) {
    $ComboBox1.Items.Add($lst)
}

...to this...

$list = @(Get-ChildItem -Directory ".\").Name
$ComboBox1.Items.AddRange($list)

...or even this...

$ComboBox1.Items.AddRange(@(Get-ChildItem -Directory ".\").Name)