Create a mandatory parameter if another parameter is chosen This topic contains 3 replies, has 3 voices, and was last updated by Don Jones 2 years, 4 months ago. Author Posts February 4, 2016 at 12:31 pm #34868 Justin KingParticipant Is it possible to define a parameter that is only mandatory if another parameter is set? fast example: param ( [parameter(mandatory=$true)][string][ValidateSet("Option1","Option2")]$Mode, [parameter][string]$Option ) Basically let's say I'd like to set $Option to mandatory but _only_ if $mode="Option2". Obviously I can do this easily enough in the script outside of the param block, but I figured I'd ask if there was a more elegant way? February 4, 2016 at 12:53 pm #34869 Dave WyattModerator Nope. You'll have to add that validation logic inside the function somewhere. (Usually in the Begin block, but might need to be in Process if either of those parameters can accept pipeline input.) February 4, 2016 at 12:53 pm #34870 Dave WyattModerator Well, technically you can use dynamic parameters, but that's even less friendly. 🙂 February 4, 2016 at 1:19 pm #34871 Don JonesKeymaster You can do what you're asking – that's what parameter sets are for – if you approach the logic slightly differently. Instead of an "Option" switch... Set A: -Option1 Set B: -Option2 -Mode Where -Mode is always mandatory, but only gets engaged if run with -Option2. This is more the pattern you see Microsoft use in the native cmdlets. Author Posts You must be logged in to reply to this topic.