Windows PowerShell Cookbook Volume 3 by Lee Holmes
There are a couple of very easy ways to get a find enum values in PowerShell. Enums are often used when choosing an option as a parameter in a PowerShell command. This article shows you exactly how to get those values for any enumerated list type (called “enum”).
The easiest way to find enum values in PowerShell is to use Get-Help, but that doesn’t always work
The easiest way is by using the Get-Help command on a PowerShell cmdlet or function. All of the built in PowerShell cmdlets have great help that is painstakingly created and maintained. Some of the functions that are included with PowerShell modules or a PSSnapin will also have documented parameters.
So the number one most simple way to check out the possible accepted values for an enum is to check with the get-help documentation.
It looks like this:
Get-Help Set-ExecutionPolicy –full
In the results, you can see in the values displayed inline with the parameter that accepts the type
Start by using Get-Help to try finding enum values. It is very fast, and the enum values are often in the help documentation.
That’s pretty good. Unfortunately, the help for a function that was developed in house does not usually include such great documentation.
The best way to find enum values with PowerShell is to use a static method.
I’ll continue to use the Set-ExecutionPolicy cmdlet as my example, but these will work for any class that is an enum.
There are two approaches to this, and each one does the same thing.
First, you can use a static method from the base enum class, [system.enum]. Secondly, you can use a static method of the class (the enum) that you’re trying to identify the values for.
And before you can do either one, you need to identify the type that the enum represents.
How to find out the type of an enum
Consider the “Set-ExecutionPolicy” cmdlet, which uses a parameter “ExecutionPolicyScope” to specify at what level you want to apply the execution policy that you’re setting.
So if you want to know what options can go in
Set-ExecutionPolicy –ExecutionPolicy RemoteSigned –Scope ???
You can find out what class the “Scope” parameter accepts by using Get-Help to interrogate the parameter.
Get-Help Set-ExecutionPolicy –Parameter Scope
Which returns just the information about the “Scope” parameter.
This shows that what you put into the Scope parameter is an object of type ExecutionPolicyScope.
That’s half the battle. Actually, it’s way more than half the battle: you’re almost done.
Finding out the names in an enumerated list (enum) when you know the type.
So now that we know the type, we need to be able to reference it.
To do this, I’m going to use a static method from the Enumeration class, SYSTEM.ENUM, called GetNames(). Use it like this:
[Enum]::GetNames(“Microsoft.PowerShell.ExecutionPolicyScope”)
And you will get all of the possible options for your enumerated list. It might look like I took some liberties with the class name, because when it was listed in the Get-Help –Parameter output from above it was listed as “ExecutionPolicyScope” but when I entered it into the GetNames static method I used “Microsoft.PowerShell.ExecutionPolicy”. When I first tried it with just “ExecutionPolicyScope” it returned an error. So I made a guess that it was part of the standard PowerShell namespace, and it turned out to be correct.
By the way, the default PowerShell namespace is Microsoft.PowerShell and many PowerShell objects that are listed as only a class name actually belong to it, so it can be worth a try.
Many other enums listed as types in parameters for a command will list out the full namespace with the object.
Ok – so you’ve read the article. I hope that you’ve gotten something great out of it. I love helping people get more out of PowerShell, because I know PowerShell can help people do more work, faster, and with fewer mistakes than ever.
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