含&符号的合法XML无法被PowerShell读取的解决求助

第三方XML文件内容（无法修改） #

C:\Temp\test.xml:

<?xml version="1.0" standalone="yes"?>
<parameters>
<setParameter name="ConnectionString" value="mongodb://svc-dev, connectTimeoutMS=300000&w=majority"/>
</parameters>

加载报错信息 #

执行PowerShell命令加载时出现以下错误：

PS C:\Users\meuser> $xml = [xml](Get-Content "C:\Temp\test.xml")
Cannot convert value "System.Object[]" to type "System.Xml.XmlDocument". Error: "'=' is an unexpected token. The expected 
token is ';'. Line 3, position 90."
At line:1 char:1
+ $xml = [xml](Get-Content "C:\Temp\test.xml")
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidArgument: (:) [], RuntimeException
    + FullyQualifiedErrorId : InvalidCastToXmlDocument

核心需求与现有代码逻辑 #

需要检查XML是否为空或包含setParameter条目，现有代码如下：

# Check if the XML contains any entries for setParameter
if ($xml.parameters.setParameter) {
    # Check if all the name and value attributes are empty
    $isEmpty = $xml.parameters.setParameter | ForEach-Object {
        $_.name -eq "" -and $_.value -eq ""
    } | Measure-Object -Maximum

    if ($isEmpty.Maximum -eq 1) {
        Write-Host "XML RESULTS: All the name and value attributes are empty."
        #exit 1;
    } else {
        Write-Host "XML RESULTS: The XML contains GOOD entries for setParameter."
    }
} else {
        Write-Host "XML RESULTS: The XML does not contain any entries for setParameter."
        exit 1;
}

注：无法修改原XML文件，后续还需读取键值对并修改后保存为新文件。

解决方案 #

报错原因是XML中value属性里的&未转义为&，不符合XML规范。由于无法修改原文件，可在加载时先读取文件内容并替换未转义的&，再转换为XML对象：

修改后的加载代码 #

# 读取文件内容并修复未转义的&
$xmlContent = (Get-Content "C:\Temp\test.xml" -Raw) -replace '&(?!amp;|lt;|gt;|quot;|apos;)', '&'
# 转换为XML对象
$xml = [xml]$xmlContent

完整验证代码 #

将上述加载逻辑和原有验证代码整合：

# 加载并修复XML
$xmlContent = (Get-Content "C:\Temp\test.xml" -Raw) -replace '&(?!amp;|lt;|gt;|quot;|apos;)', '&'
$xml = [xml]$xmlContent

# 检查setParameter条目
if ($xml.parameters.setParameter) {
    $isEmpty = $xml.parameters.setParameter | ForEach-Object {
        $_.name -eq "" -and $_.value -eq ""
    } | Measure-Object -Maximum

    if ($isEmpty.Maximum -eq 1) {
        Write-Host "XML RESULTS: All the name and value attributes are empty."
        # exit 1
    } else {
        Write-Host "XML RESULTS: The XML contains GOOD entries for setParameter."
    }
} else {
    Write-Host "XML RESULTS: The XML does not contain any entries for setParameter."
    exit 1
}

后续修改保存说明 #

如果需要修改键值对并保存为新文件，修改XML对象后直接调用Save方法即可，修复后的XML内容符合规范，保存时会自动处理转义：

# 修改示例：修改ConnectionString的value
$xml.parameters.setParameter | Where-Object { $_.name -eq "ConnectionString" } | ForEach-Object {
    $_.value = "mongodb://new-svc, connectTimeoutMS=300000&w=majority"
}
# 保存为新文件
$xml.Save("C:\Temp\modified_test.xml")

内容的提问来源于stack exchange，提问作者Ashar