ComboBox

In a ScriptoForm, the Microsoft .NET ComboBox class is a control that allows a user to interactively select one of multiple items from a drop-down style list. This selected text or index can be used to control or provide a parameter to actions performed by a ScriptoForm.

Usage

In a ScriptoForm PowerShell script file, a ComboBox control should be instantiated in the Controls region and then defined within the Forms script block. A ComboBox is usually paired with a matching Label control. If using the ScriptoForm VS Code snippets, the ScriptoForm Controls: Label & ComboBox snippet can be used to instantiate this control pair and the ScriptoForm Properties: Label & ComboBox snippet can be used to assign a default set of properties to them. By convention, this control pair should be nested in the $GroupBoxMain GroupBox container.

The steps needed to implement a ComboBox control with a ScriptoForm include:

• Instantiate a ComboBox object and an associated Label object in the Controls region.
  Suggested name format: $LabelName | $ComboBoxName
• Assign the required and any optional properties to the ComboBox object in the Forms region.
• Assign Event Handlers to the ComboBox object in the Forms region.
• Add the control pair to a GroupBox object in the Forms region.
• Define event handlers for the ComboBox with script blocks in the Handlers region.
• Add an initial list of items to the ComboBox in an appropriate event handler in the Handlers region, as needed.
• Modify the list of items in the ComboBox with appropriate event handlers in the Handlers region, as needed.
• Utilize the value of the ComboBox Text field with appropriate event handlers in the Handlers region, as needed.

Examples

1. Instantiate a new System.Windows.Forms.ComboBox and System.Windows.Forms.Label control pair:

   Controls Region

   $LabelEnvironment = New-Object -TypeName System.Windows.Forms.Label
   $ComboBoxEnvironment = New-Object -TypeName System.Windows.Forms.ComboBox

2. Assign properties to the pair, the event handler listener to the ComboBox object, and add the pair to the GroupBox object:

   Forms Region | $ShowMainForm

   $ShowFormMain =
   {
       $LabelEnvironment.Location = New-Object -TypeName System.Drawing.Point(15,70)
       $LabelEnvironment.AutoSize = $true
       $LabelEnvironment.Text = "Environment:"
       $GroupBoxMain.Controls.Add($LabelEnvironment)
   
       $ComboBoxEnvironment.Location = New-Object -TypeName System.Drawing.Point(15,90)
       $ComboBoxEnvironment.Size = New-Object -TypeName System.Drawing.Size(($FormWidth - 50),20)
       $ComboBoxEnvironment.TabIndex = 1
       $ComboBoxEnvironment.DropDownStyle = [System.Windows.Forms.ComboBoxStyle]::DropDownList
       $ComboBoxEnvironment.Add_SelectedIndexChanged($ComboBoxEnvironment_SelectedIndexChanged)
       $GroupBoxMain.Controls.Add($ComboBoxEnvironment)
   }

3. Add items to the ComboBox object and set the default index for it:

   Handlers Region | $FormMain_Load

   $FormMain_Load =
   {
       if (Test-Path -Path $EnvironmentsFile)
       {
           $ComboBoxEnvironment.Items.AddRange($(Get-Content -Path $EnvironmentsFile))
           $ComboBoxEnvironment.SelectedIndex = 0
       }
   }

4. Create the event handler for the ComboBox object:

   Handlers Region | $ComboBoxEnvironment_SelectedIndexChanged

   $ComboBoxEnvironment_SelectedIndexChanged =
   {
       if ($ComboBoxEnvironment.Text = "Production")
       {
           $TextBoxEmailAddress.Enabled = $true
       }
   }

5. Use the Text property of ComboBox object to retrive the current value:

   Forms Region | $ShowMainForm

   $Environment = $ComboBoxEnvironment.Text

Notes

The DropDownStyle property of a ComboBox determines one of three ComboBoxStyle behaviors the ComboBox will exhibit. Typically, in a ScriptoForm, the DropDownList style is used, which indicates the list is non-interactive and cannot be modified by the user.

Forms Region | $ShowMainForm

$ComboBoxEnvironment.DropDownStyle = [System.Windows.Forms.ComboBoxStyle]::DropDownList

References

ComboBox Class (System.Windows.Forms) | Microsoft Learn