How do I run a segment of powershell code from an XML element?

Question

5.00/5 (1 vote)

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I have an XML document that describes requirements. If I had Powershell code between the Values tag, could I somehow extract it and then run it?

XML

<field name="c">
        <Required>TRUE</Required>
        <Description>	 Three letter country code where the individual receives company correspondence
	 Must be set to the appropriate ISO 3166-1 "alpha-3" code.  The most common values are "USA" (United States) and "CAN" (Canada).
        </Description>
        <Values>
            Get-ADUser -filter *
        </Values>
</field>

What I have tried:

$standard = [xml] (Get-Content "C:\Users\***\Documents\Standard.xml")
$fields = $standard.SelectNodes("//UsersDefaultOU/field")
$code = $fields[0].Values

Posted 9-Jun-16 5:23am

Member 12575030

Updated 9-Jun-16 10:17am

v2

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Comments

Richard Deeming 9-Jun-16 16:10pm

Sounds like you're looking for the Invoke-Expression[^] cmdlet.

Sergey Alexandrovich Kryukov 9-Jun-16 16:21pm

Exactly. But it also takes parsing of the XML (I don't know why having it though).
Please see more detailed answer, Solution 1.
Your comment is credited.
—SA

Sergey Alexandrovich Kryukov 9-Jun-16 16:19pm

I have no idea why would you need it, and not sure this is a good idea, but it make some good and practically important question, so I up-voted it.
—SA

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Sergey Alexandrovich Kryukov · Accepted Answer · 2016-06-09T10:17:00

You have to achieve two different things: 1) parse XML in PowerShell, 2) when you extract some parameters and extract/compose a PowerShell command, execute this command.

To start with, read this short but instructional article: Using PowerShell to read xml-files | Little more than out of the box development.

From the other hand, PowerShell is a fully-fledged .NET language. Well, almost. First, you can learn how to use PowerShell to load an arbitrary assembly, first of all, from GAC, and write .NET code. When you learn it, you can use any part of .NET FCL. It offers some different ways of parsing XML. This is my short overview of them:
- Use System.Xml.XmlDocument class. It implements DOM interface; this way is the easiest and good enough if the size if the document is not too big.
  See http://msdn.microsoft.com/en-us/library/system.xml.xmldocument.aspx.
- Use the class System.Xml.XmlTextReader; this is the fastest way of reading, especially is you need to skip some data.
  See http://msdn.microsoft.com/en-us/library/system.xml.xmlreader.aspx.
- Use the class System.Xml.Linq.XDocument; this is the most adequate way similar to that of XmlDocument, supporting LINQ to XML Programming.
  See http://msdn.microsoft.com/en-us/library/system.xml.xmldocument.aspx, http://msdn.microsoft.com/en-us/library/bb387063.aspx.
The second issue is much less trivial. Here is where you can realize the power of PowerShell, compared to other technologies based on strictly compiled .NET languages: the problem is solved quite simply.

The solution is: the cmdlet "Invoke-Expression".
My credit goes to Richard Deeming with his comment to the question. :-)

—SA