Question

I’d like to use PowerShell as part of our automated build process to update an App.config file while deploying into our test environment. How can I do this?

Answer 1

Given this sample App.config: C:\Sample\App.config:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <connectionStrings>
        <add name="dbConnectionString" 
             connectionString="Data Source=(local);Initial Catalog=Northwind;Integrated Security=True"/>
    </connectionStrings>
</configuration>

The following script, C:\Sample\Script.ps1, will read and write a setting:

# get the directory of this script file
$currentDirectory = [IO.Path]::GetDirectoryName($MyInvocation.MyCommand.Path)
# get the full path and file name of the App.config file in the same directory as this script
$appConfigFile = [IO.Path]::Combine($currentDirectory, 'App.config')
# initialize the xml object
$appConfig = New-Object XML
# load the config file as an xml object
$appConfig.Load($appConfigFile)
# iterate over the settings
foreach($connectionString in $appConfig.configuration.connectionStrings.add)
{
    # write the name to the console
    'name: ' + $connectionString.name
    # write the connection string to the console
    'connectionString: ' + $connectionString.connectionString
    # change the connection string
    $connectionString.connectionString = 'Data Source=(local);Initial Catalog=MyDB;Integrated Security=True'
}
# save the updated config file
$appConfig.Save($appConfigFile)

Execute the script:

PS C:\Sample> .\Script.ps1

Output:

name: dbConnectionString  
connectionString: Data Source=(local);Initial Catalog=Northwind;Integrated Security=True

Updated C:\Sample\App.config:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <connectionStrings>
    <add name="dbConnectionString" 
         connectionString="Data Source=(local);Initial Catalog=MyDB;Integrated Security=True" />
  </connectionStrings>
</configuration>