PowerShell的：添加子節點XML

Question

我有以下XML樹：

<company> 
    <employees> 
    <employee name="Dwight" id="e1000" department="sales"> 
    </employee> 
    <employee name="Toby" id="e1001" department="hr"> 
    </employee> 
    <employee name="Jim" id="e1002" department="sales"> 
    </employee> 
    </employees> 
</company> 

而且我想在部門=「接待」添加一個名爲帕姆新員工，ID =「E1003」。

這是我到目前爲止已經試過：

$fileName = "C:\code\employees.xml"; 

$xmlDoc = [System.Xml.XmlDocument](Get-Content $fileName); 
$newXmlEmployee = $xmlDoc.employees.AppendChild($xmlDoc.CreateElement("employee")); 
$newXmlEmployee.SetAttribute("name","Pam"); 
$newXmlEmployee.SetAttribute("id","e1003"); 
$newXmlEmployee.SetAttribute("department","reception"); 

$xmlDoc.Save($fileName); 

但是我跟以下錯誤消息映入眼簾：

You cannot call a method on a null-valued expression. At C:\code\testing.ps1:6 char:48 + $newXmlEmployee = $xmlDoc.employees.AppendChild <<<< ($xmlDoc.CreateElement("employee")); + CategoryInfo : InvalidOperation: (AppendChild:String) [], RuntimeException + FullyQualifiedErrorId : InvokeMethodOnNull

You cannot call a method on a null-valued expression. At C:\code\testing.ps1:7 char:29 + $newXmlEmployee.SetAttribute <<<< ("name","Pam"); + CategoryInfo : InvalidOperation: (SetAttribute:String) [], RuntimeException + FullyQualifiedErrorId : InvokeMethodOnNull

You cannot call a method on a null-valued expression. At C:\code\testing.ps1:8 char:29 + $newXmlEmployee.SetAttribute <<<< ("id","e1003"); + CategoryInfo : InvalidOperation: (SetAttribute:String) [], RuntimeException + FullyQualifiedErrorId : InvokeMethodOnNull

You cannot call a method on a null-valued expression. At C:\code\testing.ps1:9 char:29 + $newXmlEmployee.SetAttribute <<<< ("department","reception"); + CategoryInfo : InvalidOperation: (SetAttribute:String) [], RuntimeException + FullyQualifiedErrorId : InvokeMethodOnNull

我將如何解決這個問題？

Answer 1

你幾乎明白了。你只是錯過了company節點，在您選擇employees：

$fileName = "C:\code\employees.xml"; 

$xmlDoc = [xml](Get-Content $fileName); 
$newXmlEmployee = $xmlDoc.company.employees.AppendChild($xmlDoc.CreateElement("employee")); 
$newXmlEmployee.SetAttribute("name","Pam"); 
$newXmlEmployee.SetAttribute("id","e1003"); 
$newXmlEmployee.SetAttribute("department","reception"); 

$xmlDoc.Save($fileName); 

輸出：

<company> 
    <employees> 
    <employee name="Dwight" id="e1000" department="sales"> 
    </employee> 
    <employee name="Toby" id="e1001" department="hr"> 
    </employee> 
    <employee name="Jim" id="e1002" department="sales"> 
    </employee> 
    <employee name="Pam" id="e1003" department="reception" /> 
    </employees> 
</company>