Set xml element value

Question

Im trying to set the value of an xml element, however, its simply not working. no error is thrown, but its not setting the value either.
My xml doc contains the following:
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<TMMsg_CreateTaskReq>
<Element1>
<value>val1</value>
<value>val2</value>
</Element1>
</TMMsg_CreateTaskReq>
Im trying to update the 1st value node to "new value" but the file is not updated. what am I doing wrong?
[xml]$fileContents = Get-Content -Path 'C:\test.xml'
$fileContents.TMMsg_CreateTaskReq.Element1.Value[0] = 'new value'
$fileContents.Save('C:\test2.xml')

Answer 1

Hi
From what I gather,  powershell is probably understanding that you're trying to access a member named 'Value" of Element1 instead of a child node.
If you look at
System.Xml.XmlElement, you'll see that 'value' already exists. 
You can also see it by doing:
$fileContents.TMMsg_CreateTaskReq.Element1 | get-member
by doing get-member,  you'll also see that value is read only.  Powershelll simply ignores your attemp to write to a read-only property and moves on.
I usually use xpath queries when powershell doesn't do exactly what I want:
($fileContents.SelectSingleNode("//value[1]"))."#text"="bob"
That lines select a the first node called value anywhere in the xml document, and then updates the text property to bob.