How to get the argument passed to function with switch statement?

Question

function test
{
    [CmdletBinding()]
    param
    (
        [Parameter(
            Mandatory = $true,
            ParameterSetName = "MyArgument"
        )]
        [ValidateSet("Value1", "Value2")]
        [string[]]
        $MyArguments
    )

    foreach ($MyArgument in $MyArguments)
    {
        switch ($MyArgument)
        {
            Value1
            {
                write-host "$parameter used"
            }
            Value2
            {
                write-host "$parameter used"
            }
        }
    }
}
test -MyArgument Value1, Value2

How to get the actual argument passed by parameter if we use switch? I tried to catch it by $MyInvocation.BoundParameters.Values and $PSCmdlet.MyInvocation.InvocationName, but failed.

I want to get instead of a variable $parameter Value1 if we call Value1, and Value2 if we call Value2, but all approaches receive all values at once.

Thanks in advance.

Did you mean Write-Host "$_ used" or Write-Host "$MyArgument used" ? You're switching on $MyArgument, the value you're switching on can be represented as $_ in the action block of a switch statement. — Santiago Squarzon
– Santiago Squarzon, Commented Jan 2 at 17:28
Oh, really! Ha-ha. Thanks a lot! I've complicated everything digging into $MyInvocation, Get-Command -Name $MyInvocation.MyCommand, Get-PSCallStack $MyInvocation.BoundParameters.Values, $PSCmdlet.MyInvocation.InvocationName, $ParameterList = (Get-Command -Name $MyInvocation.MyCommand).Parameters, $ParameterList["Variable"].Attributes.ValidValues — Sanctuary
– Sanctuary, Commented Jan 2 at 17:52

Santiago Squarzon · Accepted Answer · 2025-01-02 18:37:32Z

3

Because you're using a foreach loop in your function, the current argument can be represented as $MyArgument, however the item you're switching on is always represented as $_ or $PSItem in the action script block, so in this case both options are valid:

Write-Host "$MyArgument used"
# or
Write-Host "$_ used"

Something worth noting about switch in PowerShell is that it can also enumerate collections, so you can also get rid of your loop and this becomes valid code too:

function test {
    [CmdletBinding()]
    param(
        [Parameter(
            Mandatory = $true,
            ParameterSetName = 'MyArgument'
        )]
        [ValidateSet('Value1', 'Value2')]
        [string[]] $MyArguments
    )

    switch ($MyArguments) {
        Value1 {
            Write-Host "$_ used"
        }
        Value2 {
            Write-Host "$_ used"
        }
    }
}

test -MyArguments Value1, Value2

Relevant docs:

edited Jan 2 at 18:37

answered Jan 2 at 17:57

Santiago Squarzon

65.7k5 gold badges26 silver badges60 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

Sanctuary Jan 2 at 22:12

Thanks a lot. So other cases we can retrive an argument with tohse commands I mentioned above?

Santiago Squarzon Jan 2 at 22:35

Not sure why you'd want to use the commands mentioned in your comment @farag. At best, if you need to check what parameters were bound you can use $PSBoundParameters automatic variable. Aside from that, for this specific case you have a single parameter and you can get the values bound by simply using $MyArguments

Sanctuary Jan 3 at 20:06

I know, but I need to catch Value1 only as $PSBoundParameters shows all arguments: Value : {Value1, Value2}

Santiago Squarzon Jan 3 at 20:08

Yah so thats where switch ($MyArguments) { or foreach ($myArgument in $MyArguments) { come into place... @farag

Collectives™ on Stack Overflow

How to get the argument passed to function with switch statement?

1 Answer 1

4 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

4 Comments

Your Answer

Sign up or log in

Post as a guest

Related