Create extension attribute and update user object extension attributes

[merill]

# Create Tenant App to hold extension attributes
$app = New-MgApplication -DisplayName "Tenant Extension Properties App"
New-MgServicePrincipal -AppId $app.AppId

#Create new extension attribute
$extProp = New-MgApplicationExtensionProperty -Name "JobCode" -DataType "String" -TargetObjects "User" -ApplicationId $app.Id

#Update user object with extension attribute
$prop = @{}
$prop.Add($extProp.Name, "Hola")

Update-MgUser -UserId merill@pora.onmicrosoft.com -AdditionalProperties $prop

#Read the extension attribute
$u = Get-MgUser -UserId merill@elapora.com -Select extension_271b9db46e96430c808f973a776adeaf_JobCode
$u.AdditionalProperties.extension_271b9db46e96430c808f973a776adeaf_JobCode

#Remove the extension property from the user object
Invoke-GraphRequest -Method PATCH -Uri "https://graph.microsoft.com/v1.0/users/merill@elapora.com" -Body '{"extension_271b9db46e96430c808f973a776adeaf_JobCode": null}'

[Arjan-van-Rees]

I have a question regarding the extensionproperties. In this code block you create a new property and then read it. When you read it, you select it using 'extension_GUID_propertyName'. Is the GUID in this ID the App ID of the app holding the property?

What if I have an extension property but I'm not sure about the name, is there some way to read all the extension properties from a given App?

[benjiwolfe]

Running Get-MgDirectoryObjectAvailableExtensionProperty will give you all the Directory Extensions that exist across all apps in the tenant.

[glennvanrymenant]

and yes, the AppId is listed in the extension property's name.