Wednesday, October 5, 2011

Editing a web.config using PowerShell–adding a node method 1

This is an extension of a recent bunch of posts about XML and handling XML in PowerShell.

One way of adding a node and content can be accomplished by building the node out of XML objects.  Some might consider the the true ‘object’ way of working through this problem.

The bit of XML that I want to add to my web.config is:

<location path="FederationMetadata">
      <allow users="*" />

This is a walkthrough of building that as pure XML objects using PowerShell.  And then inserting it into a very specific location in the larger XML document.

First, I have to load in the web.config and make it an XML document. 

$file = get-item -path $path

$xml = [xml](get-content $file)

Now, Create the ‘location’ node as an XML document.

$federationLocation = $xml.CreateElement("location")

Set the attribute of ‘path’

$federationLocation.SetAttribute("path", "FederationMetadata") 

Create a nested node ‘system.web’

$fedSystemWebNode = $xml.CreateElement("system.web") 

Create a nested node ‘authorization’

$fedAuthNode = $xml.CreateElement("authorization")

Create the ‘allow’ element

$fedAllowNode = $xml.CreateElement("allow")

Add the ‘users’ attribute

$fedAllowNode.SetAttribute("users", "*") 

Now, for the really fun part.  And the important part to pay attention to.

Reassemble the nodes in the correct order

Begin by appending the inner mode node to its parent


Repeat with the next node and its parent


Repeat the process again


Now, I want to insert the XML document Node into a very specific place in the web.config XML configuration file.  That location is before the XML path ‘configuration/system.web’.

$xml.configuration.InsertBefore($federationLocation, ($xml.configuration.Item("system.web")))

That is it.  lots of lines. But performed in a true object style.

Oh, and don’t forget to save back to the file system.


Next time, the quick and dirty string method.


Hossein Jabbarzadeh said...

How do you check if does already exist or not. so you don't add duplicated item

BrianEh said...

You would add a test for $file being empty or $xml being empty (following the example).

Hossein Jabbarzadeh said...

Sorry I didn't ask my question properly. How do you check if the location tag ( location path="FederationMetadata" ) already does not exist in web.config. so basically if you run your script 10 times it only add the XML only once

BrianEh said...

It only adds it once, as you keep adding the same key / value in the same place of the XML document.

BrianEh said...

Just to add. A bit of search with this:

And you find this:

Not sure if that meets your intent.