xml - 在Powershell中解析XML

Question

如果我有一个XML文件，例如:

<?xml version="1.0" encoding="utf-8"?>
<package date-created="19/07/2016" version="6" system="6">
  <description />
  <system />
  <res id="1057002654" name="ABC" path="/DEF" type="F" mimeType="application/x-shared">
    <description />
    <keywords />
    <resver id="1057014163" major="1" minor="0" revision="0" effective-from="20010101000000" effective-to="20991231235959" />
    <resver id="1057014677" major="2" minor="0" revision="0" effective-from="20010101000000" effective-to="20991231235959" />
    <resver id="1057015106" major="3" minor="0" revision="0" effective-from="20010101000000" effective-to="20991231235959" />
    <resver id="1057016183" major="4" minor="0" revision="0" effective-from="20010101000000" effective-to="20991231235959" />
    <resver id="1057016374" major="5" minor="0" revision="0" effective-from="20010101000000" effective-to="20991231235959" />
    <resver id="1057017622" major="6" minor="0" revision="0" effective-from="20010101000000" effective-to="20991231235959" />
    <resver id="1057017704" major="7" minor="0" revision="0" effective-from="20010101000000" effective-to="20991231235959" />
    <resver id="1057017863" major="8" minor="0" revision="0" effective-from="20010101000000" effective-to="20991231235959" />
  </res>
</package>

可能有数百种物品，其中可能有一个或多个。在Powershell中，我尝试查找最后一个 resver id 值，其中 res id 等于 1057002654 。

我从这个开始:

$path = 'C:\TEST\package.xml'
$myxml = [xml](Get-Content $path)
$node = $myxml.package.res.resver | where {$_.id -eq "1057002654"}
$node.id = '123'
$myxml.Save($path)

这只是一个快速测试，以查看是否可以达到所需的水平并进行更新，但是失败了:

Property 'id' cannot be found on this object; make sure it exists and is settable.

然后，我尝试了类似的方法:

$xml = [xml](Get-Content 'C:\TEST\package.xml')
$nodes = $xml.SelectNodes("//*[@res]")
foreach ($node in $nodes) {

$node.Attributes | %{$_}  > C:\TEST\disk.txt }

这实际上将属性中的所有值都写入.txt文件，但似乎找不到实际执行我想要的方法。

/编辑-纠正了我的实际意图。最终得到这样的代码，其中 $ Ref 是数组 $ References 中的一项

foreach ($Ref in $References)
{
    $xml = [xml](Get-Content 'C:\TEST\package.xml')
    $res = $xml.SelectSingleNode('//res[@id = $Ref]/child::resver')
    $resource = $res.id + ".txt"

    # more stuff here
} 

虽然出现此错误:

Exception calling "SelectSingleNode" with "1" argument(s): "Namespace Manager or XsltContext needed. This query has a prefix, variable, or user-defined function."
At C:\TEST\script.ps1:22 char:38
+ [string] $res = $xml.SelectSingleNode <<<< ('//res[@id = $Ref]/child::resver')
    + CategoryInfo          : NotSpecified: (:) [], MethodInvocationException
    + FullyQualifiedErrorId : DotNetMethodException

Answer 1

在找到具有正确ID的parent::节点后，使用<resver />轴查找适当的父节点:

$path = 'C:\TEST\package.xml'
$myxml = [xml](Get-Content $path)
# Locate resver, select parent res node
$res = $myxml.SelectSingleNode('//resver[@id = "1057014163"]/parent::res')
# Update id
$res.SetAttribute('id','123')
# Save document
$myxml.Save($path)

您还可以为父节点使用 ..别名:

//resver[@id = "1057014163"]/..

或 as PetSerAl notes，选择具有所描述的子节点的 res节点:

//res[resver/@id = "1057014163"]

通过另一种方法(根据父节点 resver查找所有 id子节点 id值):

$ids = $myxml.SelectNodes('//res[@id = "1057002654"]/resver[@id]') |Select -Expand id

(注意使用 SelectNodes()而不是 SelectSingleNode())