CODEWITHSUNDEEP
powershell
julealgon
julealgon

Reputation: 8181

How can I propagate parameters from my script into internal function calls?

I'm writing a script in PowerShell and I need to pass an optional parameter that I declared as a parameter of my script into a function.

For instance, this could be a Example.ps1 file:

[CmdletBinding()]
Param(
    [string] $Param1,
    [string] $Param2,
    [string] $Param3,
    [string] $ComputerName
)

#... code that uses the first 3 parameters ...

# Here, I need to pass the 'ComputerName' parameter along:
Start-DscConfiguration -Path 'somePath -ComputerName $ComputerName -Wait

I tried two approaches using splatting, but I'm not too happy with either of them. The first one is to use the PSBoundParameters hashset like this:

PSBoundParameters.Remove('Param1');
PSBoundParameters.Remove('Param2');
PSBoundParameters.Remove('Param3');
Start-DscConfiguration -Path 'somePath @PSBoundParameters -Wait

And the second is by using a new hashtable, with the required arguments:

$dscParameters = @{
    Path = 'somePath'
};
if (-Not [string]::IsNullOrEmpty($ComputerName))
{
    $dscParameters.Add('ComputerName', $ComputerName);
}

Start-DscConfiguration @dscParameters -Wait

Is there a more elegant way of propagating my parameters to the functions that I call inside of my script? Perhaps if there was a cleaner way of constructing the hashset without including the ComputerName key if it was not supplied or something.

UPDATE:

Note that I can't just always redirect it, since it is optional and thus can be empty. If I pass an empty ComputerName to Start-DscConfiguration in this case, it will complain that it could not find computer "".

Upvotes: 1

Views: 546

Answers (3)

ojk
ojk

Reputation: 2542

[CmdletBinding()]
Param(
    [string] $Param1,
    [string] $Param2,
    [string] $Param3,
    [string] $ComputerName
)

#... code that uses the first 3 parameters ...

if (-not($PSBoundParameters['ComputerName'])){
    Start-DscConfiguration -Path 'somePath -Wait
}
else{
    Start-DscConfiguration -Path 'somePath -ComputerName $ComputerName -Wait
}

Upvotes: 0

Arluin
Arluin

Reputation: 594

I usually build a splat hashtable:

[CmdletBinding()]
Param(
    [string] $Param1,
    [string] $Param2,
    [string] $Param3,
    [string] $ComputerName
)

$DscParamHash = @{}

if($ComputerName){
   $DscParamHash.Add("-ComputerName","$ComputerName")
}

#Insert other params that you want, for example:
$DscParamHash.Add("-Wait",$true)

#Then call the cmdlet
Start-DscConfiguration @DscParamHash

Upvotes: 3

briantist
briantist

Reputation: 47812

How about this:

[CmdletBinding()]
Param(
    [string] $Param1,
    [string] $Param2,
    [string] $Param3,
    [string] $ComputerName
)

$PSDefaultParameterValues = @{
    'Start-DscConfiguration:ComputerName' = $ComputerName
}

#... code that uses the first 3 parameters ...

# Here, I need to pass the 'ComputerName' parameter along:
Start-DscConfiguration -Path 'somePath' -Wait

Reference

about_Parameter_Default_Values

Upvotes: 1

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