Using an answer file with a PowerShell script

Question

I have a PowerShell script with a number of 'params' at the start:

param(
    [switch] $whatif,
    [string] $importPath = $(Read-Host "Full path to import tool"),
    [string] $siteUrl = $(Read-Host "Enter URL to create or update"),
    [int] $importCount = $(Read-Host "Import number")
)

Is there any way I can run this against an answer file to avoid entering the parameter values every time?

Answer 1

I am not getting the reason for the question. All you have to do to call your script is something like:

.\script.ps1 -whatif -importPath import_path -siteUrl google.com -importCount 1

The Read-Host are there as defaults, to be executed ( and then read and assign the values to the parameters ) only if you don't specify the values. As long you have the above comand ( saved in a file so that you can copy and paste into console or run from another script or whatever ), you don't have to enter the values again and again.

Answer 2

Start by setting the function or script up to accept pipeline input.

[CmdletBinding(SupportsShouldProcess=$True,ConfirmImpact='Low')]
param(
  [Parameter(Mandatory=$True,ValueFromPipelineByPropertyName=$True)]
  [string] $importPath,

  [Parameter(Mandatory=$True,ValueFromPipelineByPropertyName=$True)]
  [string] $siteUrl,

  [Parameter(Mandatory=$True,ValueFromPipelineByPropertyName=$True)]
  [int] $importCount
)

Notice that I removed your manually-created -whatif. No need for it - I'll get to it in a second. Also note that Mandatory=$True will make PowerShell prompt for a value if it isn't provided, so I removed your Read-Host.

Given the above, you could create an "answer file" that is a CSV file. Make an importPath column, a siteURL column, and an importCount column in the CSV file:

importPath,siteURL,importCount
"data","data",1
"x","y",2

Then do this:

Import-CSV my-csv-file.csv | ./My-Script

Assuming your script is My-Script.ps1, of course.

Now, to -whatif. Within the body of your script, do this:

if ($pscmdlet.shouldprocess($target)) {
  # do whatever your action is here
}

This assumes you're doing something to $target, which might be a path, a computer name, a URL, or whatever. It's the thing you're modifying in your script. Put your modification actions/commands inside that if construct. Doing this, along with the SupportsShouldProcess() declaration at the top of the script, will enable -whatif and -confirm support. You don't need to code those parameters yourself.

What you're building is called an "Advanced Function," or if it's just a script than I guess it'd be an "Advanced Script." Utilizing pipeline input parameters in this fashion is the "PowerShell way of doing things."