PowerShell PowerShell Dynamic Parameters "Simple" dynamic parameter
Example
This example adds a new parameter to MyTestFunction if $SomeUsefulNumber is greater than 5.
function MyTestFunction
{
[CmdletBinding(DefaultParameterSetName='DefaultConfiguration')]
Param
(
[Parameter(Mandatory=$true)][int]$SomeUsefulNumber
)
DynamicParam
{
$paramDictionary = New-Object -Type System.Management.Automation.RuntimeDefinedParameterDictionary
$attributes = New-Object System.Management.Automation.ParameterAttribute
$attributes.ParameterSetName = "__AllParameterSets"
$attributes.Mandatory = $true
$attributeCollection = New-Object -Type System.Collections.ObjectModel.Collection[System.Attribute]
$attributeCollection.Add($attributes)
# If "SomeUsefulNumber" is greater than 5, then add the "MandatoryParam1" parameter
if($SomeUsefulNumber -gt 5)
{
# Create a mandatory string parameter called "MandatoryParam1"
$dynParam1 = New-Object -Type System.Management.Automation.RuntimeDefinedParameter("MandatoryParam1", [String], $attributeCollection)
# Add the new parameter to the dictionary
$paramDictionary.Add("MandatoryParam1", $dynParam1)
}
return $paramDictionary
}
process
{
Write-Host "SomeUsefulNumber = $SomeUsefulNumber"
# Notice that dynamic parameters need a specific syntax
Write-Host ("MandatoryParam1 = {0}" -f $PSBoundParameters.MandatoryParam1)
}
}
Usage:
PS > MyTestFunction -SomeUsefulNumber 3
SomeUsefulNumber = 3
MandatoryParam1 =
PS > MyTestFunction -SomeUsefulNumber 6
cmdlet MyTestFunction at command pipeline position 1
Supply values for the following parameters:
MandatoryParam1:
PS >MyTestFunction -SomeUsefulNumber 6 -MandatoryParam1 test
SomeUsefulNumber = 6
MandatoryParam1 = test
In the second usage example, you can clearly see that a parameter is missing.
Dynamic parameters are also taken into account with auto completion.
Here's what happens if you hit ctrl + space at the end of the line:
PS >MyTestFunction -SomeUsefulNumber 3 -<ctrl+space>
Verbose WarningAction WarningVariable OutBuffer
Debug InformationAction InformationVariable PipelineVariable
ErrorAction ErrorVariable OutVariable
PS >MyTestFunction -SomeUsefulNumber 6 -<ctrl+space>
MandatoryParam1 ErrorAction ErrorVariable OutVariable
Verbose WarningAction WarningVariable OutBuffer
Debug InformationAction InformationVariable PipelineVariable
