ComboBox.SelectedItem 给出 Null 值

Question

我整天都被困在这个问题上。我正在使用 PowerShell 表单创建 UI。其中：

• 用户从第一个组合框中选择一个选项。点击按钮前往
• 根据选择，将出现一个面板，其中包含另一个组合框。
• 如果用户在第一个组合框中选择另一个选项，则会出现另一个面板和另一个组合框
• 从面板组合框中选择选项后，用户单击开始按钮。
• 这会导致一个函数将选定的选项存储到一个变量中。

问题

• 现在，当用户从面板的组合框中选择选项时，我使用 $combobox.selecteditem.Tostring 来获取值。 但它给了我 NULL 结果。 这是我的代码..

  $global:Button1Clicked = 0;
  Add-Type -AssemblyName System.Windows.Forms
  Add-Type -AssemblyName System.Drawing
  [System.Windows.Forms.Application]::EnableVisualStyles()
  [System.Windows.Forms.FormClosingEventHandler]
  
  $Form = New-Object system.Windows.Forms.Form
  $Form.ClientSize = '1500,800'
  $Form.text = "NextUI "
  $Form.BackColor = 'White'
  $Form.TopMost = $true
  $Form.add_closing(
  {
  if($global:Button2Clicked)
  {
  $global:Button2Clicked = 0;
  
  $_.cancel = $true;
  }
  })
  
  
  $panel1 = New-Object system.Windows.Forms.Panel
  $panel1.AutoSize = $true
  $panel1.Width = 1200
  $panel1.Height = 200
  $panel1.location = New-Object System.Drawing.Point(50,100)
  $panel1.Visible = $false
  $panel1.Controls.Add($label3)
  $panel1.Controls.Add($comboBox2)
  $panel1.BorderStyle = 1
  
  
  $panel2 = New-Object system.Windows.Forms.Panel
  $panel2.AutoSize = $true
  $panel2.Width = 1200
  $panel2.Height =200
  $panel2.location = New-Object system.Drawing.Point(50,100)
  $panel2.Visible = $false
  $panel2.Controls.Add($label4)
  $panel2.Controls.Add($ComboBox3)
  $panel2.BorderStyle = 1
  
  $Label1 = New-Object system.Windows.Forms.Label
  $Label1.text = "Select Module"
  $Label1.AutoSize = $true
  $Label1.location = New-Object System.Drawing.Point(35,50)
  $Label1.Font = 'segoe ui,9.5'
  
  $Label2 = New-Object system.Windows.Forms.Label
  $Label2.text = "SharePoint Settings"
  $Label2.AutoSize = $true
  $Label2.location = New-Object System.Drawing.Point(35,15)
  $Label2.Font = 'Segoe UI Semibold,9.5'
  
  $Label3 = New-Object system.Windows.Forms.Label
  $Label3.text = "Choose file and folder permission option"
  $Label3.AutoSize = $true
  $Label3.location = New-Object System.Drawing.Point(100,200)
  $Label3.Font = 'segoe ui,9.5'
  
  
  $Label4 = New-Object system.Windows.Forms.Label
  $Label4.AutoSize = $True
  $Label4.text = "File Permission"
  $Label4.location = New-Object System.Drawing.Point(100,200)
  $Label4.Font = 'Segoe UI ,9.5'
  
  
  ################ Module combo box ################
  
  $ComboBox1 = New-Object system.Windows.Forms.ComboBox
  $ComboBox1.text = "Select Module"
  $ComboBox1.width = 200
  $ComboBox1.height = 20
  $ComboBox1.location = New-Object System.Drawing.Point(310, 45)
  $ComboBox1.Font = 'Microsoft Sans Serif,10'
  $combobox1.items.Add("ControlSettings")
  $combobox1.items.Add("NextSettings")
  
  
  ######## file and folder permission #############
  $ComboBox2 = New-Object system.Windows.Forms.ComboBox
  $ComboBox2.text = "select an option"
  $ComboBox2.width = 200
  $ComboBox2.height = 20
  $ComboBox2.location = New-Object System.Drawing.Point(450, 200)
  $ComboBox2.Font = 'Microsoft Sans Serif,10'
  $ComboBox2.items.Add("View") 
  $ComboBox2.items.Add("Edit") 
  
  $ComboBox3 = New-Object system.Windows.Forms.ComboBox
  $ComboBox3.text = "select an option"
  $ComboBox3.width = 200
  $ComboBox3.height = 20
  $ComboBox3.location = New-Object System.Drawing.Point(450, 200)
  $ComboBox3.Font = 'Microsoft Sans Serif,10'
  $ComboBox3.items.Add("View") 
  $ComboBox3.items.Add("Edit")
  
  
  Function Button2_Click()
  {
  
  if ($ComboBox1.SelectedIndex -eq 0)
  {
  $panel2.Visible = $true
  $panel1.Visible = $false
  }
  
  if ($ComboBox1.SelectedIndex -eq 1)
  {
  $panel1.Visible = $true
  $panel2.Visible = $false
  
  }
  
  
  }
  
  $Button1 = New-Object system.Windows.Forms.Button
  $Button1.text = "Start"
  $Button1.width = 150
  $Button1.height = 30
  $Button1.BackColor = '#F6CEE3'
  $Button1.DialogResult = [System.Windows.Forms.DialogResult]::OK
  $Button1.location = New-Object System.Drawing.Point(500, 700)
  $Button1.Font = 'segoe ui,10'
  $Button1.Add_Click({
  Button1_Click;
  $global:Button1Clicked = 1;
  })
  
  ############# Button 'Go' #############
  
  $Button2 = New-Object system.Windows.Forms.Button
  $Button2.text = "Go"
  $Button2.width = 100
  $Button2.height = 30
  $Button2.BackColor = '#F6CEE3'
  $Button2.DialogResult = [System.Windows.Forms.DialogResult]::OK
  $Button2.location = New-Object System.Drawing.Point(680, 43)
  $Button2.Font = 'segoe ui,10'
  $Button2.Add_Click({
  Button2_Click;
  $global:Button2Clicked = 1;
  })
  
  
  ######### code Starts ###########
  
  function Button1_Click()
  {
      $link = $comboBox2.SelectedItem.ToString();
      $linktype = $comboBox3.SelectedItem.ToString();
  
  
  }
  ####### end of code ######
  
  $form.Controls.Add($Panel1)
  $form.Controls.Add($Panel2)
  $form.Controls.Add($button1)
  $form.Controls.Add($comboBox1)
  $form.Controls.Add($button2)
  $form.Controls.Add($pictureBox1)
  $form.Controls.Add($label1)
  $form.Controls.Add($label2)
  
  [void]$Form.Add_Shown({ $Form.Activate() })
  [void]$Form.ShowDialog()

Answer 1

问题是您的变量是在函数中设置的，因此它们的作用域是该函数。真的没有理由把它放在一个函数中，而是直接把它放在.add_click() 中。或者，如果您觉得需要将其保留在函数中，您可以像使用 $global:ButtonClicked 一样设置变量的范围，并将它们设置为 $global:Link 和 $global:LinkType。

编辑：顺序确实对 PowerShell 产生了影响，因此我确实在您的脚本中移动了一些内容以使其正常工作，但是当我放置它们时，我能够获得反映良好的值在全局范围内。

$global:Button1Clicked = 0;
Add-Type -AssemblyName System.Windows.Forms
Add-Type -AssemblyName System.Drawing
[System.Windows.Forms.Application]::EnableVisualStyles()
[System.Windows.Forms.FormClosingEventHandler]

######### code Starts ###########

function Button1_Click()
{
    write-host "Link = $global:link"
    write-host "Link Type = $global:linktype"

}

Function Button2_Click()
{

if ($ComboBox1.SelectedIndex -eq 0)
{
$panel2.Visible = $true
$panel1.Visible = $false
}

if ($ComboBox1.SelectedIndex -eq 1)
{
$panel1.Visible = $true
$panel2.Visible = $false

}


}

####### end of code ######

$Form = New-Object system.Windows.Forms.Form
$Form.ClientSize = '1500,800'
$Form.text = "NextUI "
$Form.BackColor = 'White'
$Form.TopMost = $true
$Form.add_closing(
{
if($global:Button2Clicked)
{
$global:Button2Clicked = 0;

$_.cancel = $true;
}
})

################ Module combo box ################

$ComboBox1 = New-Object system.Windows.Forms.ComboBox
$ComboBox1.text = "Select Module"
$ComboBox1.width = 200
$ComboBox1.height = 20
$ComboBox1.location = New-Object System.Drawing.Point(310, 45)
$ComboBox1.Font = 'Microsoft Sans Serif,10'
$combobox1.items.Add("ControlSettings")
$combobox1.items.Add("NextSettings")


######## file and folder permission #############
$ComboBox2 = New-Object system.Windows.Forms.ComboBox
$ComboBox2.text = "select an option"
$ComboBox2.width = 200
$ComboBox2.height = 20
$ComboBox2.location = New-Object System.Drawing.Point(450, 200)
$ComboBox2.Font = 'Microsoft Sans Serif,10'
$ComboBox2.items.AddRange(@("View","Edit") )
#$ComboBox2.items.Add("Edit") 

$ComboBox3 = New-Object system.Windows.Forms.ComboBox
$ComboBox3.text = "select an option"
$ComboBox3.width = 200
$ComboBox3.height = 20
$ComboBox3.location = New-Object System.Drawing.Point(450, 200)
$ComboBox3.Font = 'Microsoft Sans Serif,10'
$ComboBox3.items.Add("View") 
$ComboBox3.items.Add("Edit")

$panel1 = New-Object system.Windows.Forms.Panel
$panel1.AutoSize = $true
$panel1.Width = 1200
$panel1.Height = 200
$panel1.location = New-Object System.Drawing.Point(50,100)
$panel1.Visible = $false
$panel1.Controls.Add($label3)
$panel1.Controls.Add($comboBox2)
$panel1.BorderStyle = 1


$panel2 = New-Object system.Windows.Forms.Panel
$panel2.AutoSize = $true
$panel2.Width = 1200
$panel2.Height =200
$panel2.location = New-Object system.Drawing.Point(50,100)
$panel2.Visible = $false
$panel2.Controls.Add($label4)
$panel2.Controls.Add($ComboBox3)
$panel2.BorderStyle = 1

$Label1 = New-Object system.Windows.Forms.Label
$Label1.text = "Select Module"
$Label1.AutoSize = $true
$Label1.location = New-Object System.Drawing.Point(35,50)
$Label1.Font = 'segoe ui,9.5'

$Label2 = New-Object system.Windows.Forms.Label
$Label2.text = "SharePoint Settings"
$Label2.AutoSize = $true
$Label2.location = New-Object System.Drawing.Point(35,15)
$Label2.Font = 'Segoe UI Semibold,9.5'

$Label3 = New-Object system.Windows.Forms.Label
$Label3.text = "Choose file and folder permission option"
$Label3.AutoSize = $true
$Label3.location = New-Object System.Drawing.Point(100,200)
$Label3.Font = 'segoe ui,9.5'


$Label4 = New-Object system.Windows.Forms.Label
$Label4.AutoSize = $True
$Label4.text = "File Permission"
$Label4.location = New-Object System.Drawing.Point(100,200)
$Label4.Font = 'Segoe UI ,9.5'


$Button1 = New-Object system.Windows.Forms.Button
$Button1.text = "Start"
$Button1.width = 150
$Button1.height = 30
$Button1.BackColor = '#F6CEE3'
$Button1.DialogResult = [System.Windows.Forms.DialogResult]::OK
$Button1.location = New-Object System.Drawing.Point(500, 700)
$Button1.Font = 'segoe ui,10'
$Button1.Add_Click({
$global:link = $comboBox2.SelectedItem.ToString();
$global:linktype = $comboBox3.SelectedItem.ToString();
Button1_Click;
$global:Button1Clicked = 1;
})

############# Button 'Go' #############

$Button2 = New-Object system.Windows.Forms.Button
$Button2.text = "Go"
$Button2.width = 100
$Button2.height = 30
$Button2.BackColor = '#F6CEE3'
$Button2.DialogResult = [System.Windows.Forms.DialogResult]::OK
$Button2.location = New-Object System.Drawing.Point(680, 43)
$Button2.Font = 'segoe ui,10'
$Button2.Add_Click({
Button2_Click;
$global:Button2Clicked = 1;
})

$form.Controls.Add($Panel1)
$form.Controls.Add($Panel2)
$form.Controls.Add($button1)
$form.Controls.Add($comboBox1)
$form.Controls.Add($button2)
$form.Controls.Add($pictureBox1)
$form.Controls.Add($label1)
$form.Controls.Add($label2)

[void]$Form.Add_Shown({ $Form.Activate() })
[void]$Form.ShowDialog()

当我运行它时，设置两个组合框值，然后单击“开始”，我在 ISE 中看到了我将 Link 和 LinkType 变量设置为的文本，并且能够回显 $global:link 和 $global:linktype 以查看值正确分配。