PowerShell - create a variable from an existing XML node sibling

First off, let me mention that I am a beginner at PowerShell and would like to thank everyone for their help in advance

I have a function in a PowerShell script that creates numerous new XML nodes using

$fileElement = $xml.CreateElement("FileRef")
$fileElement.SetAttribute("Id",$refId)

This works fine so I have several node siblings 开发者_开发百科called FileRef, each with different Id attributes. The $fileElement variable gets used again later on in the script where it gets it's own child nodes added, using $fileElement.AppendChild.

I now have circumstances where I have a loop that calls the script function multiple times passing in the same $refId variable. The problem I have is that the output is getting duplicated FileRef node siblings with the same id.

What I would like to do, under certain circumstances, is create the $fileElement variable from an existing FileRef node sibling with the id = $refId (so that I can still use AppendChild on the variable later on in the script) instead of create a new XML node sibling with the id = $refId (which is causing the duplication). E.g.

if(circumstances) 
{
    # first call to the function in the loop, so create new node sibling
    $fileElement = $xml.CreateElement("FileRef")
    $fileElement.SetAttribute("Id",$refId)
}
else 
{
    # node sibling already exists, do not create new node,  
    # use existing node sibling with id = $refId
    create xml node variable $fileElement here
}

Thanks

Ok, I've managed to solve my problem with the following PowerShell code:

if(circumstances)
{
    $fileElement = $xml.CreateElement("fileRef")
    $directoryRefElement.SetAttribute("Id",$refId)      
}
else # use existing node
{
    $fileElement = ""
    $currentNode = $xml.get_Item("fileRef")

    do
    {
        $currentId = $currentNode.GetAttribute("Id")
        if ($currentId -eq $refId)
        {
            $fileElement = $currentNode
        }
        else
        {
            $tempNode = $currentNode
            $currentNode = $tempNode.get_NextSibling()
        }
    }
    while($fileElement -eq "")
}

When I need to find an existing node sibling, I get the first node of the type I'm looking for and check it's Id attribute against the passed in $refId. If they do not match, I will look at the next sibling and so on until the 2 ids match.

While this may not be the most elegant way to achieve my goal, it does work nonetheless :-)