PowerShell串口命令发送JSON字符串时语法解析错误求助

问题描述 #

编写PowerShell脚本通过COM连接执行设备基础配置，收集用户输入后拼接压缩JSON字符串通过USB发送。不含JSON的命令（如重启）可正常执行，但JSON字符串因PowerShell语法规则导致脚本报错。

报错信息 #

At line:146 char:22
+     $port.Write("3,{"bankName":"$bankName","bankId":"0","footswitches ...
+                      ~
Missing ')' in method call.
At line:146 char:22
+ ... .Write("3,{"bankName":"$bankName","bankId":"0","footswitches":[{"name ...
+                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Unexpected token 'bankName":"$bankName","bankId":"0","footswitches":[{"name":"$FS1
"},{"name":"$FS2"},{"name":"$FS3"},{"name":"$FS4"},{"name":"$FS5"},{"name":"$FS6"}
]}~"' in expression or statement.
At line:126 char:1
+ {
+ ~
Missing closing '}' in statement block or type definition.
At line:146 char:172
+ ... ,{"name":"$FS3"},{"name":"$FS4"},{"name":"$FS5"},{"name":"$FS6"}]}~")
+                                                                         ~
Unexpected token ')' in expression or statement.
At line:149 char:1
+ }
+ ~
Unexpected token '}' in expression or statement.
    + CategoryInfo          : ParserError: (:) [], ParentContainsErrorRecordExcep 
   tion
    + FullyQualifiedErrorId : MissingEndParenthesisInMethodCall

完整脚本 #

Add-Type -AssemblyName System.Windows.Forms
Add-Type -AssemblyName System.Drawing

$form = New-Object System.Windows.Forms.Form
$form.Text = 'Bridge Namer'
$form.Size = New-Object System.Drawing.Size(300,400)
$form.StartPosition = 'CenterScreen'

$okButton = New-Object System.Windows.Forms.Button
$okButton.Location = New-Object System.Drawing.Point(75,320)
$okButton.Size = New-Object System.Drawing.Size(75,23)
$okButton.Text = 'OK'
$okButton.DialogResult = [System.Windows.Forms.DialogResult]::OK
$form.AcceptButton = $okButton
$form.Controls.Add($okButton)

$cancelButton = New-Object System.Windows.Forms.Button
$cancelButton.Location = New-Object System.Drawing.Point(150,320)
$cancelButton.Size = New-Object System.Drawing.Size(75,23)
$cancelButton.Text = 'Cancel'
$cancelButton.DialogResult = [System.Windows.Forms.DialogResult]::Cancel
$form.CancelButton = $cancelButton
$form.Controls.Add($cancelButton)

$label = New-Object System.Windows.Forms.Label
$label.Location = New-Object System.Drawing.Point(10,20)
$label.Size = New-Object System.Drawing.Size(280,20)
$label.Text = 'What Bank Number do you want to Re-Name?'
$form.Controls.Add($label)

$textBoxbankNumber = New-Object System.Windows.Forms.TextBox
$textBoxbankNumber.Location = New-Object System.Drawing.Point(10,40)
$textBoxbankNumber.Size = New-Object System.Drawing.Size(260,20)
$form.Controls.Add($textBoxbankNumber)

$label = New-Object System.Windows.Forms.Label
$label.Location = New-Object System.Drawing.Point(10,70)
$label.Size = New-Object System.Drawing.Size(280,20)
$label.Text = 'New Bank Name:'
$form.Controls.Add($label)

$textBoxbankName = New-Object System.Windows.Forms.TextBox
$textBoxbankName.Location = New-Object System.Drawing.Point(10,90)
$textBoxbankName.Size = New-Object System.Drawing.Size(260,20)
$form.Controls.Add($textBoxbankName)

$label = New-Object System.Windows.Forms.Label
$label.Location = New-Object System.Drawing.Point(10,120)
$label.Size = New-Object System.Drawing.Size(120,20)
$label.Text = 'Footswitch 1 Name:'
$form.Controls.Add($label)

$textBoxFS1 = New-Object System.Windows.Forms.TextBox
$textBoxFS1.Location = New-Object System.Drawing.Point(10,140)
$textBoxFS1.Size = New-Object System.Drawing.Size(120,20)
$form.Controls.Add($textBoxFS1)

$label = New-Object System.Windows.Forms.Label
$label.Location = New-Object System.Drawing.Point(150,120)
$label.Size = New-Object System.Drawing.Size(120,20)
$label.Text = 'Footswitch 2 Name:'
$form.Controls.Add($label)

$textBoxFS2 = New-Object System.Windows.Forms.TextBox
$textBoxFS2.Location = New-Object System.Drawing.Point(150,140)
$textBoxFS2.Size = New-Object System.Drawing.Size(120,20)
$form.Controls.Add($textBoxFS2)

$label = New-Object System.Windows.Forms.Label
$label.Location = New-Object System.Drawing.Point(10,170)
$label.Size = New-Object System.Drawing.Size(120,20)
$label.Text = 'Footswitch 3 Name:'
$form.Controls.Add($label)

$textBoxFS3 = New-Object System.Windows.Forms.TextBox
$textBoxFS3.Location = New-Object System.Drawing.Point(10,190)
$textBoxFS3.Size = New-Object System.Drawing.Size(120,20)
$form.Controls.Add($textBoxFS3)

$label = New-Object System.Windows.Forms.Label
$label.Location = New-Object System.Drawing.Point(150,170)
$label.Size = New-Object System.Drawing.Size(120,20)
$label.Text = 'Footswitch 4 Name:'
$form.Controls.Add($label)

$textBoxFS4 = New-Object System.Windows.Forms.TextBox
$textBoxFS4.Location = New-Object System.Drawing.Point(150,190)
$textBoxFS4.Size = New-Object System.Drawing.Size(120,20)
$form.Controls.Add($textBoxFS4)

$label = New-Object System.Windows.Forms.Label
$label.Location = New-Object System.Drawing.Point(10,220)
$label.Size = New-Object System.Drawing.Size(120,20)
$label.Text = 'Footswitch 5 Name:'
$form.Controls.Add($label)

$textBoxFS5 = New-Object System.Windows.Forms.TextBox
$textBoxFS5.Location = New-Object System.Drawing.Point(10,240)
$textBoxFS5.Size = New-Object System.Drawing.Size(120,20)
$form.Controls.Add($textBoxFS5)

$label = New-Object System.Windows.Forms.Label
$label.Location = New-Object System.Drawing.Point(150,220)
$label.Size = New-Object System.Drawing.Size(120,20)
$label.Text = 'Footswitch 6 Name:'
$form.Controls.Add($label)

$textBoxFS6 = New-Object System.Windows.Forms.TextBox
$textBoxFS6.Location = New-Object System.Drawing.Point(150,240)
$textBoxFS6.Size = New-Object System.Drawing.Size(120,20)
$form.Controls.Add($textBoxFS6)

$form.Topmost = $true

$form.Add_Shown({$textBoxbankNumber.Select()})
$form.Add_Shown({$textBoxbankName.Select()})
$form.Add_Shown({$textBoxFS1.Select()})
$form.Add_Shown({$textBoxFS2.Select()})
$form.Add_Shown({$textBoxFS3.Select()})
$form.Add_Shown({$textBoxFS4.Select()})
$form.Add_Shown({$textBoxFS5.Select()})
$form.Add_Shown({$textBoxFS6.Select()})
$result = $form.ShowDialog()

if ($result -eq [System.Windows.Forms.DialogResult]::OK)
{
    $bankNumber = $textBoxbankNumber.Text   
    $bankName = $textBoxbankName.Text    
    $FS1 = $textBoxFS1.Text   
    $FS2 = $textBoxFS2.Text 
    $FS3 = $textBoxFS3.Text
    $FS4 = $textBoxFS4.Text  
    $FS5 = $textBoxFS5.Text
    $FS6 = $textBoxFS6.Text

    $port= new-Object System.IO.Ports.SerialPort COM6,9600,None,8,one
    $port.DtrEnable = "true"
    $port.open()
    Start-Sleep -Milliseconds 50
    $port.Write("0,RSET~")
    Start-Sleep -Milliseconds 50
    $port.Write("1,DTXR~")
    Start-Sleep -Milliseconds 50
    $port.Write("2,bankSettings,$bankNumber~")
    Start-Sleep -Milliseconds 50
    $port.Write("3,{"bankName":"$bankName","bankId":"0","footswitches":[{"name":"$FS1"},{"name":"$FS2"},{"name":"$FS3"},{"name":"$FS4"},{"name":"$FS5"},{"name":"$FS6"}]}~")
    Start-Sleep -Milliseconds 50
    $port.close()
}

解决办法 #

报错核心原因是PowerShell双引号字符串内的JSON双引号未转义，导致解析混淆。以下三种简单方式可解决：

方式1：转义JSON中的双引号 #

在JSON的每个双引号前添加反引号（`），让PowerShell将其视为普通字符：

$port.Write("3,{`"bankName`":`"$bankName`",`"bankId`":`"0`",`"footswitches`":[{`"name`":`"$FS1`"},{`"name`":`"$FS2`"},{`"name`":`"$FS3`"},{`"name`":`"$FS4`"},{`"name`":`"$FS5`"},{`"name`":`"$FS6`"}]}~")

方式2：使用Here-String #

Here-String可保留字符串原样，无需手动转义双引号，适合复杂JSON场景：

$jsonPayload = @"
3,{"bankName":"$bankName","bankId":"0","footswitches":[{"name":"$FS1"},{"name":"$FS2"},{"name":"$FS3"},{"name":"$FS4"},{"name":"$FS5"},{"name":"$FS6"}]}~
"@
$port.Write($jsonPayload)

方式3：用ConvertTo-JSON生成规范JSON（推荐） #

先创建PowerShell对象，再转换为压缩JSON，彻底避免手动拼接的语法错误：

$bankConfig = [PSCustomObject]@{
    bankName = $bankName
    bankId = "0"
    footswitches = @(
        @{ name = $FS1 },
        @{ name = $FS2 },
        @{ name = $FS3 },
        @{ name = $FS4 },
        @{ name = $FS5 },
        @{ name = $FS6 }
    )
}
$jsonString = $bankConfig | ConvertTo-Json -Compress
$port.Write("3,$jsonString~")

内容的提问来源于stack exchange，提问作者grelbatron