How to iterate the irregularly-named children of an Xml.XmlElement in Powershell?

问题

I have an XML file of the following format:

<xml>
    <data>
        <foo float="99.0"/>
        <bar float="12.0"/>
        <tribble bool="true"/>
        ...
        <flibble int="1"/>
    </data>
</xml>

If I fetch that data in Powershell, I can see all the child elements of data with a Get-Memeber:

> $xmlData = [xml](Get-Content myfile.xml)
> $xmlData.data | Get-Member
    ...
    foo     Property    System.Xml.XmlElement ...
    bar     Property    System.Xml.XmlElement ...
    tribble Property    System.Xml.XmlElement ...
    ...

And I can access each child element individually. But how would I iterate over all the children, processing them with pipes? I'd love to be able to write something like this:

> $xmlData.data.Children | ?{$_ -eq "foo"}

...But alas that's just wishful thinking.

EDIT: Ok so I can reflect on the properties like this:

> $xmlData.data | get-member -memberType Property | ?{$_.Name -eq "foo"}

But I can't then go from the property (above I'm operating on a MemberDefinition) to the actual child element. Or can I?

回答1:

First: You need to use Get-Member -Force ... which will show you everything. Note with particular interest the get_* methods which represent properties which for some reason aren't exposed as properties in PowerShell. So when you see get_ChildNodes in the member list, it means there's a .ChildNodes property on the object (even though PowerShell hides it for some reason).

Second: So therefore, there are lots of ways, including the get-member method you hinted at (I append the Format-Table because it makes it easier to tell that you got something):

$xmlData.data.SelectNodes("*") | ft name, OuterXml
$xmlData.data.ChildNodes | ft name, OuterXml
$xmlData.data | gm -type Property | % { $xmlData.data.($_.Name) } | Where { $_ -is [Xml.XmlElement] } | ft Name, OuterXml

回答2:

For some reason Get-Member doesn't display the other properties System.Xml.XmlElement provides. Here is the full member list: http://msdn.microsoft.com/en-us/library/system.xml.xmlelement_members.aspx

As you can see, there is a ChildNodes property, so you can do this:

(Select-Xml -Path "file.xml" -XPath "//xml/data").Node.ChildNodes | Where-Object { $_.Name -eq "foo" }

来源：https://stackoverflow.com/questions/3389541/how-to-iterate-the-irregularly-named-children-of-an-xml-xmlelement-in-powershell

标签

xml

powershell

powershell-2.0