getting registry entry and then adding to it - powershell

Question

I am trying to get a registry key value , ExtensionSettings, if there is something in the registry then save it. Then add a new entry to it . The two entries have to have a comma in-between values. I can not figure the code out . I am not sure what I am doing wrong or missing. Thank you so much for your help.
# Set variables to indicate value and key to set
$RegistryPath = 'HKLM:SOFTWARE\Policies\Google\Chrome'
$Name = 'ExtensionSettings'
$Value = '{"feolagkacappiaieohahjkeaikhjjcfa":{"toolbar_pin":"force_pinned"}}'
# Create the key if it does not exist
If (-NOT (Test-Path $RegistryPath)) {
New-Item -Path $RegistryPath -Force | Out-Null
}
#$OldValue = Get-ItemProperty -Path $RegistryPath -Name $Name
#$oldValue = $OldValue.ExtensionSettings
$OldValue = (Get-ItemProperty "HKLM:SOFTWARE\Policies\Google\Chrome").ExtensionSettings
#$NewValue = New-ItemProperty -Path $RegistryPath -Name $Name -Value $value
$UpdatedValue = $OldValue + "," + $NewValue
$NewValue = $NewValue.ExtensionSettings
New-ItemProperty -Path $RegistryPath -Name $Name -Value $UpdatedValue -PropertyType String -Force
Here is the error I get. I have updated the code with what I have tried . Nothing is written to the registry key. It goes show the comma but not the rest.
error I receive is
New-ItemProperty : The property already exists.
At line:15 char:13
+ $NewValue = New-ItemProperty -Path $RegistryPath -Name $Name -Value $ ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : ResourceExists: (HKEY_LOCAL_MACH...s\Google\Chrome:String) [New-ItemProperty], IOException
+ FullyQualifiedErrorId : System.IO.IOException,Microsoft.PowerShell.Commands.NewItemPropertyCommand

Answer 1

The "Extension Settings" registry key is a JSON-formatted string, so you won't be able to simply concatenate on to the end of it. Here's a sample string that Google provides as an example . . . notice that the entire string is encapsulated in curly braces. In order to add an entry, you'd have to add it inside the outer set of curly braces.
{
"*": {
"installation_mode": "blocked"
},
"nckgahadagoaajjgafhacjanaoiihapd": {
"installation_mode": "force_installed",
"update_url":
"https://clients2.google.com/service/update2/crx"
},
"lpcaedmchfhocbbapmcbpinfpgnhiddi": {
"installation_mode": "normal_installed",
"update_url":
"https://clients2.google.com/service/update2/crx"
},
"gmbgaklkmjakoegficnlkhebmhkjfich": {
"installation_mode": "allowed"
}
}
Something like the following should work (note that the original $Value has been modified to remove the outer curly braces):
# Set variables to indicate value and key to set
$RegistryPath = 'HKLM:SOFTWARE\Policies\Google\Chrome'
$Key = 'ExtensionSettings'
$ValueAdd = '"feolagkacappiaieohahjkeaikhjjcfa":{"toolbar_pin":"force_pinned"}'
# Check for existing 'ExtensionSettings' key and modify/create
If ((Get-Item -Path $RegistryPath).GetValue($Key) -ne $null) {
# Copy existing value (without outer braces)
$string = (Get-ItemProperty "$RegistryPath").$Name
$ValueOld = $string.subString(1, ($string.Length)-2)
# Modify to add new value (and add outer braces)
$ValueNew = "{$ValueOld, $ValueAdd}"
New-ItemProperty -Path $RegistryPath -Name $Key -Value $ValueNew -PropertyType String -Force
} else {
# If it doesn't already exist, create it
$ValueNew = "{$ValueAdd}"
New-ItemProperty -Path $RegistryPath -Name $Key -Value $ValueNew -PropertyType String -Force
}