select-object -expandproperty with null property

Question

I have a collection of objects with properties like id, username, email, current_sign_in_at, identities. Where Identities property is an array of objects with two properties. This would be a json representation of an object:

{
        "id": 45,
        "name": "Emilio Roche",
        "username": "EROCHE",
        "state": "active",
        "identities": [
            {
                "provider": "ldapmain",
                "extern_uid": "cn=roche\\, emilio,ou=xxxxxxxxxx"
            }    
          ]
    }

But some of the elements in the list do not have the identities property. So, when I do:

Get-Collection | Select-Object id, username  -ExpandProperty identities

I get only those elements with identities property. I need all the entities, with or without identities property

Answer 1

If there are not too many properties to handle, you could use something like this:

Get-Collection | Select-Object id, 
    username,
    @{n='provider';e={$_.identities.provider}}, 
    @{n='extern_uid';e={$_.identities.extern_uid}}

This will return $null on the properties provider and extern_uid for those objects, that do not have the identities property:

id username provider extern_uid                     
-- -------- -------- ----------                     
45 EROCHE   ldapmain cn=roche\, emilio,ou=xxxxxxxxxx
46 EROCHE                                           

---

EDIT

As mklement0 pointed out, that approach doesn't work, if the identities property holds more than one object.

mklement0's answer has an elegant solution to this problem and should have been the accepted answer.