使用PowerShell通过xml-节点嵌套循环

Question

我想从xml文件中提取所有窗口和所有视点节点的名称属性的值。

<?xml version='1.0' encoding='utf-8' ?> 
     <workbook> 
      <windows> 
       <window class='dashboard' name='D1'> 
        <viewpoints> 
        <viewpoint name='V1'> </viewpoint> 
        <viewpoint name='V2'> </viewpoint> 
        <viewpoint name='V3'> </viewpoint> 
       </viewpoints> 
       </window> 
       <window class='dashboard' name='D2'> 
        <viewpoints> 
        <viewpoint name='V10'> </viewpoint> 
        <viewpoint name='V11'> </viewpoint> 
        </viewpoints> 
       </window> 
      </windows> 
     </workbook> 

这是我写的代码：

[XML]$doc = get-content -path 'W:\Demo1.xml' 


$objs = @() 
$dashboards = $doc.SelectNodes("//window[@class = 'dashboard']") 

foreach ($dashboard in $dashboards) 
{ 
    $worksheets = $dashboard.SelectNodes("//viewpoint[@name]") 

    foreach ($worksheet in $worksheets) 
    { 
     $obj = new-object psobject -prop @{Dashboard=$dashboard.name; Worksheet = $worksheet.name}; 
     $objs += $obj; 

    } 
} 

$objs 

---

我期待什么：

 
dashboard worksheet 
D1   V1 
D1   V2 
D1   V3 
D2   V10 
D2   V11 

我得到了什么：

 
dashboard worksheet 
D1   V1 
D1   V2 
D1   V3 
D1   V10 
D1   V11 
D1   V14 
D2   V1 
D2   V2 
D2   V3 
D2   V10 
D2   V11 
D2   V14 

这里有什么问题？结果与我对嵌套循环如何工作的理解完全矛盾。

Answer 1

以/字符开头的XPath表示它将从文档根节点开始。要从上下文节点创建相对XPath，您需要在/之前放置.。

所以，你的代码应该是：

[XML]$doc = get-content -path 'W:\Demo1.xml' 


$objs = @() 
$dashboards = $doc.SelectNodes("//window[@class = 'dashboard']") 

foreach ($dashboard in $dashboards) 
{ 
    $worksheets = $dashboard.SelectNodes(".//viewpoint[@name]") 

    foreach ($worksheet in $worksheets) 
    { 
     $obj = new-object psobject -prop @{Dashboard=$dashboard.name; Worksheet = $worksheet.name}; 
     $objs += $obj; 

    } 
} 

$objs 

Answer 2

你也可以简化并采用您的xpath选择从仪表盘窗口中的所有viewpoint节点：

[XML]$doc = get-content -path 'W:\Demo1.xml' 

$objs = @() 
$worksheets = $doc.SelectNodes("//window[@class = 'dashboard']//viewpoint[@name]") 

foreach ($worksheet in $worksheets) 
{ 
    $obj = new-object psobject -prop @{Dashboard=$worksheet.ParentNode.ParentNode.name; Worksheet = $worksheet.name}; 
    $objs += $obj; 
} 

$objs 

在这里，一个解决方案，而xpath：

[XML]$doc = get-content -path 'W:\Demo1.xml' 

$objs = $doc.DocumentElement.windows.window | Where class -eq 'dashboard' | foreach { 
    $dashboardName = $_.name 
    $_.viewpoints.viewpoint | foreach { 
     new-object psobject -prop @{Dashboard=$dashboardName; Worksheet = $_.name} 
    } 
}