How to implement `DynamicParam` through dynamic parameters? - powershell

Question

Assumption:
$a = 1,2,3
if $a =1,2
Intent:Display parameter b
PS >test -<tab>
a
PS >test -a 1 -<tab>
b
PS >test -a 3 -<tab>
PS >test -a 3
How to achieve the following intent
Function test {
[CmdletBinding()]
Param()
DynamicParam {
parameter a
Dynamic parameter b (a is 1 =$true)
Dynamic parameter c (b is 3)
???
}
}

Answer 1

You don't have to assume. Research it.
What Dynamics Params are and how to use them if a fully documented use case via the MS docs site and many blog posts.
Searching for 'powershell dynamics parameters', will give you a solid list. Be sure to read the details, so as to limit any confusion about their use case.
Examples:
How can I pass dynamic parameters to powershell script and iterate
over the list?
Cmdlet dynamic parameters
PowerShell Deep Dive: Discovering dynamic parameters
Dynamic Parameters in PowerShell
How To Implement Dynamic Parameters in Your PowerShell Functions
enter link description here
# Example from the above link.
function Get-ConfigurationFile
{
[OutputType([System.IO.FileInfo])]
[CmdletBinding()]
param
()
DynamicParam
{
$ParamAttrib = New-Object System.Management.Automation.ParameterAttribute
$ParamAttrib.Mandatory = $true
$ParamAttrib.ParameterSetName = '__AllParameterSets'
$AttribColl = New-Object System.Collections.ObjectModel.Collection[System.Attribute]
$AttribColl.Add($ParamAttrib)
$configurationFileNames = Get-ChildItem -Path 'C:\ConfigurationFiles' | Select-Object -ExpandProperty Name
$AttribColl.Add((New-Object System.Management.Automation.ValidateSetAttribute($configurationFileNames)))
$RuntimeParam = New-Object System.Management.Automation.RuntimeDefinedParameter('FileName', [string], $AttribColl)
$RuntimeParamDic = New-Object System.Management.Automation.RuntimeDefinedParameterDictionary
$RuntimeParamDic.Add('FileName', $RuntimeParam)
return $RuntimeParamDic
}
process
{
$configFileFolder = 'C:\ConfigurationFiles'
Get-ChildItem -Path $configFileFolder -Filter "$($PSBoundParameters.FileName).txt"
}
}
As for this...
As you can see,tabs cannot return a parameter
..., what you are showing is not the way this use case works.
Based on what you seem to be after, this sampler should get you there. please read the whole article for a better understanding.
Dynamic Parameters in PowerShell
Function Get-Order {
[CmdletBinding()]
Param(
[Parameter(
Mandatory=$true,
Position=1,
HelpMessage="How many cups would you like to purchase?"
)]
[int]$cups,
[Parameter(
Mandatory=$false,
Position=2,
HelpMessage="What would you like to purchase?"
)]
[ValidateSet("Lemonade","Water","Tea","Coffee")]
[string]$product="Lemonade"
)
Process {
$order = #()
for ($cup = 1; $cup -le $cups; $cup++) {
$order += "$($cup): A cup of $($product)"
}
$order
}
}
Or this one...
Using Dynamic Parameters
function Test-Department
{
[CmdletBinding()]
param
(
[Parameter(Mandatory=$true)]
[ValidateSet('Microsoft','Amazon','Google','Facebook')]
$Company
)
dynamicparam
{
# this hash table defines the departments available in each company
$data = #{
Microsoft = 'CEO', 'Marketing', 'Delivery'
Google = 'Marketing', 'Delivery'
Amazon = 'CEO', 'IT', 'Carpool'
Facebook = 'CEO', 'Facility', 'Carpool'
}
# check to see whether the user already chose a company
if ($Company)
{
# yes, so create a new dynamic parameter
$paramDictionary = New-Object -TypeName System.Management.Automation.RuntimeDefinedParameterDictionary
$attributeCollection = New-Object -TypeName System.Collections.ObjectModel.Collection[System.Attribute]
# define the parameter attribute
$attribute = New-Object System.Management.Automation.ParameterAttribute
$attribute.Mandatory = $false
$attributeCollection.Add($attribute)
# create the appropriate ValidateSet attribute, listing the legal values for
# this dynamic parameter
$attribute = New-Object System.Management.Automation.ValidateSetAttribute($data.$Company)
$attributeCollection.Add($attribute)
# compose the dynamic -Department parameter
$Name = 'Department'
$dynParam = New-Object -TypeName System.Management.Automation.RuntimeDefinedParameter($Name,
[string], $attributeCollection)
$paramDictionary.Add($Name, $dynParam)
# return the collection of dynamic parameters
$paramDictionary
}
}
end
{
# take the dynamic parameters from $PSBoundParameters
$Department = $PSBoundParameters.Department
"Chosen department for $Company : $Department"
}
}
As well as this step by step one with full explanations...
How To: Add Dynamic Parameters to Your PowerShell Functions
As noted in my initial response, there are plenty of examples of this use case, but it requires study to fully grasp the concept, and how to use it/them.