Matching Powershell XML output to schema

Question

I have a monitoring system that returns JSON data. I am using Powershell to get all of the monitored servers and a subset of their properties. Then I want to export those properties to an XML file that matches an XSD, but I am not sure how to do that.

When I run

$allServers | get-member

I can see all of the properties for the servers in a System.Management.Automation.PSCustomObject. So I run:

$filtered = $allServers | Select-Object Id,HostName,Description,Status

Okay, now I have the properties I want and I can run something like this:

$filtered = ($filtered | ConvertTo-Xml)

and now I have a System.Xml.XmlDocument object. Super. I can use the save method:

$filtered.Save("c:\test\test.xml")

The output looks okay, but does not match the required schema file.

<?xml version="1.0" encoding="utf-8"?>
<Objects>
  <Object Type="System.Management.Automation.PSCustomObject">
    <Property Name="id" Type="System.Int32">6</Property>
    <Property Name="hostname" Type="System.String">server1</Property>
    <Property Name="description" Type="System.String">dc</Property>
    <Property Name="status" Type="System.Int32">1</Property>
  </Object>
</Objects>

My schema looks like this:

<?xml version="1.0" encoding="Windows-1252"?>
<xs:schema xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xs="http://www.w3.org/2001/XMLSchema" attributeFormDefault="unqualified" elementFormDefault="qualified">
  <xsd:element name="ServerImport">
    <xsd:complexType>
      <xsd:sequence>
        <xsd:element name="Servers">
          <xsd:complexType>
            <xsd:sequence>
              <xsd:element maxOccurs="unbounded" name="Server">
                <xsd:complexType>
                  <xsd:sequence>
                    <xsd:element name="Id" type="xsd:int" />
                    <xsd:element name="HostName" type="xsd:string" />
                    <xsd:element name="Description" type="xsd:string" />
                    <xsd:element name="Status" type="xsd:int" />
                  </xsd:sequence>
                </xsd:complexType>
              </xsd:element>
            </xsd:sequence>
          </xsd:complexType>
        </xsd:element>
      </xsd:sequence>
    </xsd:complexType>
  </xsd:element>
</xs:schema>

So, how do I make my output match the schema?

Thanks.

Seems like you would need to convert the output from Select-Object to a defined class. What version of Powershell are you using? — Forty3
– Forty3, Commented Mar 29, 2017 at 22:10
I think the server that will run my task currently has 4, but I can install 5. — StackExchangeGuy
– StackExchangeGuy, Commented Mar 30, 2017 at 0:26
If you can find a v5 environment, you can try converting the output to a class and then writing it to XML. Purely theory at this point as I haven't installed v5 yet, either. — Forty3
– Forty3, Commented Mar 30, 2017 at 0:33
Seems that naive approach is a no-go. Just installed v5 and ConvertTo-Xml on an object STILL results in <Objects><Object Type="car"><Property Name="make" Type="System.String">Chevy</Property></Object></Objects>. — Forty3
– Forty3, Commented Mar 30, 2017 at 13:29

Forty3 · Accepted Answer · 2017-03-30 14:34:12Z

v5 of PowerShell supports proper class structures. Therefore, you could create a class which contains the information you desire and a small-ish function to convert the class to an XmlNode:

function makeXML($parentNode, $class) {

    $d = $parentNode.OwnerDocument.CreateElement($class.GetType().Name);
    $class.psobject.properties | foreach {
        $p = $doc.CreateElement($_.Name);
        $p.InnerText = $_.Value;
        $d.AppendChild($p);
    }

    $parentNode.AppendChild($d);
}

class Server { 
    [int]$Id; 
    [string]$HostName; 
    [string]$Description; 
    [int]$Status 
};

# Here you would need to convert the output from 
#     Select-Object ID,HostName,Description,Status
# to instances of type Server 

$s = New-Object server;
$s.Id = 1;
$s.HostName = "localhost";
$s.Description = "Local Server";
$s.Status = 3;

# Create the empty XML document to save your results to with root node of "Servers"
$doc = New-Object System.Xml.XmlDocument;
$doc.LoadXml("<ServerImport><Servers></Servers></ServerImport>");
$serversNode = $doc.SelectSingleNode("/ServerImport/Servers");

# This could likely be a pipe operation against your list of Server objects
# $filtered | { makeXml $serversNode $_ }
makeXML $serversNode $s;
# Save your xml to a file
$doc.Save("C:\test\test.xml");

Which results in the following XML:

<ServerImport>
  <Servers>
    <Server>
      <Id>1</Id>
      <HostName>localhost</HostName>
      <Description>Local Server</Description>
      <Status>3</Status>
    </Server>
  </Servers>
</ServerImport>

Note: I am sure there are more elegant solutions and there are probably a dozen enhancements the above code endure. But, this should get you started.

Edit - overlooked the needed structure of the XML (missed the ServerImport root node).

I ended up using the System.XMl.XmlTextWriter class, but I like your answer too. I am definitely going to keep this in mind for next time. Thanks.

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