Test-DynamicParameters

Test-DynamicParameters.ps1

function Test-DynamicParameters {
    # CmdletBinding is mandatory for using dynamic parameters
    [CmdletBinding(DefaultParameterSetName = "default")]
    param (
        # One DynamicParam will only be usable if $name contains at least 2 elements
        [Parameter(mandatory = $false)]
        [ValidateNotNullOrEmpty()]
        [String[]]
        $Name

    )
    DynamicParam {
        # Create a dictionary that holds all dynamic parameters
        $paramDictionary = [System.Management.Automation.RuntimeDefinedParameterDictionary]::new()

        # create a parameter attribute that contains the properties like help, mandatory, position etc. https://bit.ly/3RGsZI6
        $paramAttributes = [System.Management.Automation.ParameterAttribute]::new()
        $paramAttributes.Mandatory = $false
        $paramAttributes.HelpMessage = "This is the help for DynParam"
        $paramAttributes.ParameterSetName = "__AllParameterSets"

        # create an attributecollection and add attributes to the list
        $attributeCollection = [System.Collections.ObjectModel.Collection[System.Attribute]]::new()
        $attributeCollection.Add($paramAttributes)

        # declare the Parameter and add of to the dictionary of dynamic parameters
        $parameterName = "DynParam"
        $parameterDefinition = [System.Management.Automation.RuntimeDefinedParameter]::new( $parameterName, [String], $attributeCollection)
        $paramDictionary.Add($parameterName, $parameterDefinition)

        # create a second dynamic parameter depending on the value of an other parameter. In this case if the parameter name hast more than 2 elements
        # conditional dynamic parameters can't be found on the help nor can you find the by tabbing through the parameters!!!!!!!
        if ($Name.length -gt 1) {

            # create a parameter attribute that contains the properties like help, mandatory, position etc. https://bit.ly/3RGsZI6
            $paramAttributes = [System.Management.Automation.ParameterAttribute]::new()
            $paramAttributes.Mandatory = $true

            # create an attributecollection and add attributes to the list
            $attributeCollection = [System.Collections.ObjectModel.Collection[System.Attribute]]::new()
            $attributeCollection.Add($paramAttributes)

            # declare the Parameter and add of to the dictionary of dynamic parameters
            $parameterName = "ConditionalDynParam"
            $parameterDefinition = [System.Management.Automation.RuntimeDefinedParameter]::new( $parameterName, [switch], $attributeCollection)
            $paramDictionary.Add($parameterName, $parameterDefinition)

        }

        # publish the parameter
        return $paramDictionary
    }
    # when using dynamic parameter you need a Process block
    Process {
        # dynamic parameters can't be accessed directly.
        # dynamic parameters can only be accessed through $PSBoundParameters
        $dynParam = $PSBoundParameters.DynParam
        $conditionalDynParam = $PSBoundParameters.ConditionalDynParam

        if ($dynParam) {
            Write-Host "dynParam has the value: $dynParam"
        }
        if ($conditionalDynParam) {
            Write-Host "Name Array = $Name"
            Write-Host "conditional dynamic param is $conditionalDynParam"
        }
    }
}

<#
PS > Test-DynamicParameters -Name "foo","bar" -DynParam 'param'  -ConditionalDynParam
dynParam has the value: param
Name Array = foo bar
conditional dynamic param is True

PS > Test-DynamicParameters -Name "foo"  -ConditionalDynParam
Test-DynamicParameters: A parameter cannot be found that matches parameter name 'ConditionalDynParam'.
This fails because the condition is not met

PS > Test-DynamicParameters -DynParam 'param'
dynParam has the value: param
#>