Adding an xml fragment to an existing document-CodePudding

What is the least effort way to insert an xml fragment into an existing [xml] value ([xml] of course is syntactic sugar for System.Xml.XmlDocument)?

For example, say we have this newrelic.config file:

<configuration xmlns="urn:newrelic-config" agentEnabled="true">
  <service licenseKey="**redacted**" />
  <application>
    <name>My Application</name>
  </application>
  <log level="info" />
  <transactionTracer enabled="true" transactionThreshold="apdex_f" stackTraceThreshold="500" recordSql="obfuscated" explainEnabled="false" explainThreshold="500" />
  <crossApplicationTracer enabled="true" />
  <errorCollector enabled="true">
    <ignoreErrors>
      <exception>System.IO.FileNotFoundException</exception>
      <exception>System.Threading.ThreadAbortException</exception>
    </ignoreErrors>
    <ignoreStatusCodes>
      <code>401</code>
      <code>404</code>
    </ignoreStatusCodes>
  </errorCollector>
  <browserMonitoring autoInstrument="true" />
  <threadProfiling>
    <ignoreMethod>System.Threading.WaitHandle:InternalWaitOne</ignoreMethod>
    <ignoreMethod>System.Threading.WaitHandle:WaitAny</ignoreMethod>
  </threadProfiling>
</configuration>

And we want to insert an instrumentation node under configuration; not just one element but a whole fragment:

  <instrumentation>
    <applications>
      <application name="MyApplication.exe" />
    </applications>
  </instrumentation>

Most other answers on SO flail around a lot with creating XML elements and attributes; for example this one:

 # Create ExitProcess node
  $exitProcessNode = $Document.CreateElement('ExitProcess')

  # Create ProcessName node, add process name as inner text
  $processNameNode = $Document.CreateElement('ProcessName')
  $processNameNode.InnerText = $ProcessName

  # Create ForceClose node, add setting as inner text 
  $forceCloseNode = $Document.CreateElement('ProcessName')
  $ForceCloseNode.InnerText = $ForceClose.IsPresent

How can I make this shorter?

Note: I don't have huge documents so performance is not really an issue; I'm more after shorter PowerShell code.

CodePudding user response：

The correct way to do this is to import the node (ImportNode) in the main document and than append the concerned child (AppendChild) to the specific node:

$Main = [xml]'
<configuration xmlns="urn:newrelic-config" agentEnabled="true">
  <service licenseKey="**redacted**" />
  <application>
    <name>My Application</name>
  </application>
  <log level="info" />
  <transactionTracer enabled="true" transactionThreshold="apdex_f" stackTraceThreshold="500" recordSql="obfuscated" explainEnabled="false" explainThreshold="500" />
  <crossApplicationTracer enabled="true" />
  <errorCollector enabled="true">
    <ignoreErrors>
      <exception>System.IO.FileNotFoundException</exception>
      <exception>System.Threading.ThreadAbortException</exception>
    </ignoreErrors>
    <ignoreStatusCodes>
      <code>401</code>
      <code>404</code>
    </ignoreStatusCodes>
  </errorCollector>
  <browserMonitoring autoInstrument="true" />
  <threadProfiling>
    <ignoreMethod>System.Threading.WaitHandle:InternalWaitOne</ignoreMethod>
    <ignoreMethod>System.Threading.WaitHandle:WaitAny</ignoreMethod>
  </threadProfiling>
</configuration>'

$Fragment = [xml]'
  <instrumentation>
    <applications>
      <application name="MyApplication.exe" />
    </applications>
  </instrumentation>'

$NewNode = $Main.ImportNode($Fragment.instrumentation, $True)
$Main.Configuration.AppendChild($NewNode)

[System.Xml.Linq.XDocument]::Parse($Main.OuterXml).ToString()

<configuration xmlns="urn:newrelic-config" agentEnabled="true">
  <service licenseKey="**redacted**" />
  <application>
    <name>My Application</name>
  </application>
  <log level="info" />
  <transactionTracer enabled="true" transactionThreshold="apdex_f" stackTraceThreshold="500" recordSql="obfuscated" explainEnabled="false" explainThreshold="500" />
  <crossApplicationTracer enabled="true" />
  <errorCollector enabled="true">
    <ignoreErrors>
      <exception>System.IO.FileNotFoundException</exception>
      <exception>System.Threading.ThreadAbortException</exception>
    </ignoreErrors>
    <ignoreStatusCodes>
      <code>401</code>
      <code>404</code>
    </ignoreStatusCodes>
  </errorCollector>
  <browserMonitoring autoInstrument="true" />
  <threadProfiling>
    <ignoreMethod>System.Threading.WaitHandle:InternalWaitOne</ignoreMethod>
    <ignoreMethod>System.Threading.WaitHandle:WaitAny</ignoreMethod>
  </threadProfiling>
  <instrumentation xmlns="">
    <applications>
      <application name="MyApplication.exe" />
    </applications>
  </instrumentation>
</configuration>

CodePudding user response：

This function appends a string xml fragment as a child of an xmlelement:

function AppendChildXml {
     param (
         [System.Xml.XmlElement]$element,
         [string]$fragment
     )
     [System.Xml.XmlDocumentFragment]$fragxml = $element.OwnerDocument.CreateDocumentFragment();
     $fragxml.innerXml = $fragment;
     $element.AppendChild($fragxml);
}

Since the function has an XmlElement as its first parameter, this makes it easy to mix with the "PowerShell way" of referring to deep elements with properties, e.g. $xmldoc.configuration.errorCollector.ignoreErrors

For example:

# read in the existing newrelic.config
[xml]$newRelicConfigXml = [xml]::new();
$newRelicConfigXml.Load((Convert-Path $newRelicConfigPath));

# instrumentation section to be added
[string]$fragment = '<instrumentation><applications><application name="MyApplication.exe"/></applications></instrumentation>'

# add instrumentation under configuration
AppendChildXml $newRelicConfigXml.configuration $fragment