Get infos returned by a labellink in a richtextbox (.NET FORMS)

Question

I have a problem to get the information returned by my labelLink into a richtextbox.

I've got text in the RichTextBox and I create the Labellink like this.

$Textlink = New-Object System.Windows.Forms.LinkLabel
$Textlink.text = "AMIGA"
$Textlink.Name = "AMIGALINK"
$Textlink.add_LinkClicked($Textlink_LinkClicked)
$ClassicRTB1.Controls.Add($Textlink)

It's adding an AMIGA clickable link in my RichTextBox named $ClassicRTB1

I have done this powershell statement when the button is clicked

$Textlink_LinkClicked = {
$ClassicRTB1.Clear()
$message = $_.linktext
$ClassicRTB1.AppendText("$message  `n") }

It's well executing the line $ClassicRTB1.Clear() but I have nothing returned into the variable $_ for .linktext :(

I tried a lot of code all the day and found nothing ... Is what I'm doing wrong ?

Answer 1

tl;dr

# This assumes that you've actually assigned a URL to the 
# $TextLink instance - see the bottom section for how to do that.
$Textlink_LinkClicked = {

  # Declare the event delegate's parameters.
  param($evtSender, $evtArgs)

  # Retrieve the target info (typically, a URL) associated 
  # with the link that was clicked.
  $message = $evtArgs.Link.LinkData

  $ClassicRTB1.AppendText("$message  `n") 

}

---

Building on Mathias' helpful comments:

• Your primary problem is your mistaken attempt to refer to the event sender (the link-label object) via $_, which is the wrong automatic variable to use.

  • In the simplest case, use the automatic $this variable.

  • Alternatively, given that the script block receives the usual event-delegate arguments - the event's sender and the event's arguments - you can refer to them via the automatic $args variable:

    • $args[0] also refers to the event sender, and $args[1] to the event arguments.
    • A more descriptive, but more verbose alternative is to formally declare parameters for these arguments: param($evtSender, $evtArgs), as shown in the top section.

  • Note:

    • Event-related automatic variables such as $Sender are not available - they only apply to script blocks passed to the -Action parameter of the Register-ObjectEvent and Register-EngineEvent cmdlets.

• Your secondary problem is that a LinkLabel instance has no .LinkText property.^[1]

  • Instead, such an instance has a collection of links stored in the .Links property, and each LinkLabel.Link element of that collection has a .Data property containing the target data (typically, a URL string, but technically it can be any object)

    • One link is present by default, and here's an example of how you would set it:

      $Textlink.Links[0].LinkData = 'https://example.org'
      

  • Because a single link-label can potentially house multiple links - if configured, for multiple substrings of its label (.Text property) - the robust approach to respond to a click is not to examine the link-label instance itself, but to to use the event arguments to tell you which specific link was actually clicked.

    • The .Link property of the event-arguments object passed to the event delegate identifies its specific link, whose .Data property contains the link's target.

---

^{[1] You may be thinking of the .LinkText property of the event-arguments object that is available if you respond to the LinkClicked event of a RichTextBox instance itself, in response to clicking a link that that instance itself provides, due to recognizing raw URLs in its text (and, in .NET (Core), also RTF hyperlinks assigned via .Rtf) and turning them into clickable links.}