ComboBox.SelectedItem为null

时间:2019-05-24 12:53:51

标签: powershell combobox selecteditem

我用AD SamAccountName项填充了一个组合框。选择其中一项时,可以按下按钮以从该帐户中检索信息。但是,当单击按钮时,出现以下错误

Cannot validate argument on parameter 'Identity'. The argument is null. Provide a valid value for the argument, and then try running the command again.

错误所指的命令是:

$Label_User_ItemContent.Text = (Get-ADUser -Identity $ComboBox.SelectedItem).SamAccountName

该代码的关键部分是:

        $ComboBox = New-Object -TypeName System.Windows.Forms.ComboBox
        $ComboBox.Width = 300
        $ComboBox.Location = New-Object -TypeName System.Drawing.Point(250, 25)

        $Users = Get-ADUser -Filter * | Where-Object {$_.SamAccountName -match '^adminA'}
        ForEach ($User in $Users){
            $ComboBox.Items.Add($User.SamAccountName)
        }
        $ComboBox.SelectedIndex = 1

            $MainWindow.Controls.Add($ComboBox)

        $Button_Check_TEST = New-Object -TypeName System.Windows.Forms.Button
        $Button_Check_TEST.Location = New-Object -TypeName System.Drawing.Size(350, 150)
        $Button_Check_TEST.Size = New-Object -TypeName System.Drawing.Size(150, 50)
        $Button_Check_TEST.Text = 'Check'

        $MainWindow.Controls.Add($Button_Check_TEST)

        $Button_Check_TEST.Add_Click({
            Try{
                $Label_User_ItemContent.Text = (Get-ADUser -Identity $ComboBox.SelectedItem).SamAccountName
            }
            Catch{
                Write-Verbose -Verbose $_.Exception.Message
            }
        })

问题是,我需要两层。基本上,应该有一个包含四个不同选项的菜单,其中一个是“用户”。单击“用户”时,将出现组合框和“单击”按钮。 在没有“用户”按钮的情况下使用上面的代码可以正常工作。

问题:为什么我使用按钮“创建” ComboBox时ComboBox.SelectedItem不起作用?

完整的代码如下:

    $font = New-Object -TypeName System.Drawing.Font("Times New Roman", 18, [System.Drawing.FontStyle]::Bold)

    $MainWindow = New-Object -TypeName System.Windows.Forms.Form
    $MainWindow.Text = 'PIM v10 Administrator Window'
    $MainWindow.Width = 600
    $MainWindow.Height = 555
    $MainWindow.AutoSize = $true

    $Button_User = New-Object -TypeName System.Windows.Forms.Button
    $Button_User.Location = New-Object -TypeName System.Drawing.Size(25, 25)
    $Button_User.Size = New-Object -TypeName System.Drawing.Size(200, 75)
    $Button_User.Text = 'User'
    $Button_User.Font = $font

        $MainWindow.Controls.Add($Button_User)

    $Button_User.Add_Click({
    $Label_User = New-Object -TypeName System.Windows.Forms.Label
    $Label_User.Text = 'Given Name:'
    $Label_User.Location = New-Object -TypeName System.Drawing.Point(250, 50)
    $Label_User.AutoSize = $true

        $MainWindow.Controls.Add($Label_User)

    $Label_User_ItemContent = New-Object -TypeName System.Windows.Forms.Label
    $Label_User_ItemContent.Text = ''
    $Label_User_ItemContent.Location = New-Object -TypeName System.Drawing.Point(250, 100)

        $MainWindow.Controls.Add($Label_User_ItemContent)

    $ComboBox = New-Object -TypeName System.Windows.Forms.ComboBox
    $ComboBox.Width = 300
    $ComboBox.Location = New-Object -TypeName System.Drawing.Point(250, 25)

    $Users = Get-ADUser -Filter * | Where-Object {$_.SamAccountName -match '^adminA'}
     ForEach ($User in $Users){
         $ComboBox.Items.Add($User.SamAccountName)
        }
     $ComboBox.SelectedIndex = 1

        $MainWindow.Controls.Add($ComboBox)

     $Button_Check_TEST = New-Object -TypeName System.Windows.Forms.Button
     $Button_Check_TEST.Location = New-Object -TypeName System.Drawing.Size(350, 150)
     $Button_Check_TEST.Size = New-Object -TypeName System.Drawing.Size(150, 50)
     $Button_Check_TEST.Text = 'Check'

     $MainWindow.Controls.Add($Button_Check_TEST)

     $Button_Check_TEST.Add_Click({
            Try{
                $Label_User_ItemContent.Text = (Get-ADUser -Identity $ComboBox.SelectedItem).SamAccountName
            }
            Catch{
                Write-Verbose -Verbose $_.Exception.Message
            }
        })

     if (-not ($ComboBox.SelectedItem -eq $null)){
         $Label_User_ItemContent.Text = (Get-ADUser -Identity $ComboBox.SelectedItem).SamAccountName
     }
     else {
        Write-Host -Object "Object is null"
     }
    })
    $MainWindow.ShowDialog()

1 个答案:

答案 0 :(得分:1)

所以发生的事情是您在错误的范围内创建了变量

Function<Object, String>

由于要在Add_click动作中创建组合和标签。这些值仅在执行操作时和在$Button_User.Add_Click({ $ComboBox = New-Object -TypeName System.Windows.Forms.ComboBox $Label_User_ItemContent = New-Object -TypeName System.Windows.Forms.Label $MainWindow.Controls.Add($ComboBox) $Label_User_ItemContent = New-Object -TypeName System.Windows.Forms.Label $Button_Check_TEST.Add_Click({ $Label_User_ItemContent.Text = (Get-ADUser -Identity $ComboBox.SelectedItem).SamAccountName )} }) 中存在。然后从内存中清除项目

当您执行下一个操作$MainWindows.Controls时,由于变量已清除,因此$Button_Check_TEST.Add_Click()$ComboBox等于零。

一种解决方法是将它们放置在$Label_User_ItemContent事件之外

$Button_User.Add_Click()

现在整个脚本都处于工作状态

$ComboBox = New-Object -TypeName System.Windows.Forms.ComboBox
$Label_User_ItemContent = New-Object -TypeName System.Windows.Forms.Label
$Button_User.Add_Click({
    $MainWindow.Controls.Add($ComboBox)
    $Label_User_ItemContent = New-Object -TypeName System.Windows.Forms.Label
    $Button_Check_TEST.Add_Click({
        $Label_User_ItemContent.Text = (Get-ADUser -Identity 
        $ComboBox.SelectedItem).SamAccountName
    )}
})