Inbox: Expanding Properties in PowerShell

I received this in my inbox this morning:

As a quick refresher, the -expandProperty parameter of Select-Object will grab the contents of a property. In this example:

Get-ADComputer -filter * | Select -expand Name

The "Name" property of an ADComputer object contains a string, so the -expandProperty parameter produces just that string. In other words, the above command produces a bunch of computer names as simple String objects.

However, if the property you give -expandProperty is a collection, you get the objects in the collection:

Get-Job | Select -expand ChildJobs

Because the ChildJobs property of a Job object contains one or more additional Job objects, the above command would list those jobs - usually in a table format.

So why doesn't this work to do the same thing?

(Get-ADComputer –filter * ).name

Because in that case, I would expect Get-ADComputer to return multiple objects, and this syntax won't work if the parenthetical expression has multiple objects. Now, if for some reason your domain only contained one computer object, then the above syntax would work. The idea is that the "dot notation," as its called, only works with individual objects. If the parenthetical expression evaluates to a single object, the dot notation works. Thats' why this will work:

(get-date).second

It works because Get-Date only ever returns a single object. Of course, I personally find the parenthetical dot notation stuff - like the above example - to be a bit programmer-y. I tend to stick with a command-line style of syntax:

Get-Date | Select -expand second

In this case, the command-line style of syntax is longer, but it's more consistent with using the shell as a shell and not a programming language, which is what I tend to do. Also, the above syntax, using Select-Object -expandProperty, will work with one object or multiple objects, so it's a syntax that works in a broader range of situations.