The PowerShell function parameter is set to the optional and required method _powershell

This article describes the use of a parameter set in PowerShell custom functions by setting the same argument to optional and mandatory.

OK, small make admits, this topic is a bit boring, but it is still a little interesting, might as well take a look at it.

In PowerShell, we might have the requirement that this parameter is optional if you only need to enter a parameter. But if you have to enter other parameters, then this parameter becomes a must choice. So how does this need to be met? That is the meaning of this article.

Copy Code code as follows:

function Connect-somewhere
{
[Cmdletbinding (defaultparametersetname= ' A ')]
Param
(
[Parameter (Parametersetname= ' A ', mandatory= $false)]
[Parameter (Parametersetname= ' B ', mandatory= $true)]
$ComputerName,
[Parameter (Parametersetname= ' B ', mandatory= $false)]
$Credential
)
$chosen = $PSCmdlet. Parametersetname
"You have chosen $chosen parameter set."
}

Read the above function, is there any doubt? The above PowerShell function defines a set of two parameters, one with a parameter set named A, and the other named B. Parameter set A has only one parameter $computername, and it is optional. and the parameter set B has two parameters $computername and $credential. If we use parameter set a, the input does not need to enter computername This parameter, because it is not required. And if we use the parameter set B, this time we have to fill in the $computername.

And look at the following function call example.

Copy Code code as follows:

Ps> Connect-somewhere
You have chosen A parameter set.
Ps> connect-somewhere-computername Test
You have chosen A parameter set.
Ps> Connect-somewhere-credential User1
Cmdlet Connect-somewhere at command pipeline position 1
Supply values for the following parameters:
computername:nowmandatory!
You have chosen B parameter set.

The first invocation case is to use the default parameter set, in which the default parameter set is the parameter set a, the parameter set a has only one argument $computername, and is optional, so it is OK to enter nothing.

The second invocation case uses a computername parameter, conforms to the condition of parameter set a, and automatically matches the parameter set a.
The third invocation case uses only one credential parameter, which appears in the parameter set B. However, if you use parameter set B, you must fill in the ComputerName parameter, so the error is correct.

On the PowerShell function parameters can be selected and must be selected, this article on the introduction of so many, I hope to help you, thank you!