Quick Learn – PSMonday #5: Monday, May 30, 2016

Topic: Splatting and Hash Tables

Notice: This post is a part of the PowerShell Monday series — a group of quick and easy to read mini lessons that briefly cover beginning and intermediate PowerShell topics. As a PowerShell enthusiast, this seemed like a beneficial way to ensure those around me at work were consistently learning new things about Windows PowerShell. At some point, I decided I would share these posts here, as well. Here’s the PowerShell Monday Table of Contents.

There are a couple things in Windows PowerShell that have a strange name. One of them, is splatting.

Consider one of those cmdlets that requires several parameters and parameter values. The below command is an older, modified command that was used to create a PowerShell Web Access authorization rule. This command, is likely going to take up some space and either wrap in the console, or add the need to scroll horizontally in the ISE.

# This example is a lengthy, single command.

Add-PswaAuthorizationRule -RuleName SharePoint-AppAdmins-Rule -ComputerName 'SPCA01' -UserGroupName MYDOMAIN\SP-AppAdmins -ConfigurationName Tools.SharePoint

The length of this command makes it difficult to read and comprehend. Some might be inclined to use the backtick (`) as a line continuation character to help make it more readable.

# This example uses backticks as line continuation characters.

Add-PswaAuthorizationRule `
-RuleName SharePoint-AppAdmins-Rule `
-ComputerName 'SPCA01' `
-UserGroupName MYDOMAIN\SP-AppAdmins `
-ConfigurationName Tools.SharePoint

This option helps some, but I’d recommend not using the backtick as a line continuation character in about 99% of instances. It’s tiny, it’s difficult to see, and if there’s a space after it, the command will throw an error.

Back to splatting. When you splat your parameters and parameter values, you first create a hash table, as signified by @{}. For those that may not know, a hash table contains key-value pairs. The first key in the below example, is RuleName. The associated, first value is ‘SharePoint-AppAdmins-Rule’. Hash tables are also called dictionary objects, or more often, associative arrays. Here’s an example of creating and storing a hash table in a variable with the same parameters and parameter values used in the above examples.

$Parameters = @{
    RuleName = 'SharePoint-AppAdmins-Rule'
    ComputerName = 'SPCA01'
    UserGroupName = 'MYDOMAIN\SP-AppAdmins'
    ConfigurationName = 'Tools.SharePoint'
}

Now, that’s easy on the eyes. Enter the variable name to see the key-value pairs stored in the hash table.

$Parameters

Name                           Value
----                           -----
RuleName                       SharePoint-AppAdmins-Rule
ComputerName                   SPCA01
UserGroupName                  MYDOMAIN\SP-AppAdmins
ConfigurationName              Tools.SharePoint

Now when you run the command, you enter the cmdlet name, the @ symbol, and the name used for the variable (without the dollar sign), as seen in the below example.

Add-PswaAuthorizationRule @Parameters

Now, when this command is run, it will include all the parameters and parameter values defined in our hash table. That’s it for this week. We’ll pick up next week and talk a little more about splatting.