Good afternoon
Unfortunately, PowerShell is not able to detect the ParameterSet by the Parameter Types, for example: If the 2nd Parameter is passed as a Int, then select ParameterSet1, otherwise use ParameterSet2.
Therefore I would like to manually detect the passed Parameter-Combinations.
Is it possible to get the list of passed parameters in DynamicParam, something like this?:
Function Log {
[CmdletBinding()]
Param ()
DynamicParam {
# Is is possible to access the passed Parameters?,
# something like that:
If (Args[0].ParameterName -eq 'Message') { … }
# Or like this:
If (Args[0].Value -eq '…') { … }
}
…
}
Thanks a lot for any help and light!
Thomas
This first finding was wrong!:
"I've found the magic, by using $PSBoundParameters we can access the passed parameters."
This is the correct but very disappointing answer:
It's very annoying and unbelievable, but it looks like PowerShell does not pass any information about the dynamically passed arguments.
The following example used the New-DynamicParameter function as defined here:
Can I make a parameter set depend on the value of another parameter?
Function Test-DynamicParam {
[CmdletBinding()]
Param (
[string]$FixArg
)
DynamicParam {
# The content of $PSBoundParameters is just
# able to show the Params declared in Param():
# Key Value
# --- -----
# FixArg Hello
# Add the DynamicParameter str1:
New-DynamicParameter -Name 'DynArg' -Type 'string' -HelpMessage 'DynArg help'
# Here, the content of $PSBoundParameters has not been adjusted:
# Key Value
# --- -----
# FixArg Hello
}
Begin {
# Finally - but too late to dynamically react! -
# $PSBoundParameters knows all Parameters (as expected):
# Key Value
# --- -----
# FixArg Hello
# DynArg World
}
Process {
…
}
}
# Pass a fixed and dynamic parameter
Test-DynamicParam -FixArg 'Hello' -DynArg 'World'
Related
I want to wrap a function, that is to create a new function such that it would automatically pass some arguments to the old function, like python's partial functions. The arguments passed are the ones defined in the callee and not the caller. The important thing is that I don't want to refer to each of them explicitly (define them twice).
That is really done to save typing-in the same flags to complicated functions while allowing customization.
For example, in python, I would do:
call_with_x=partial(call,x=1)
or maybe use **kw and pass it to the callee in some cases .
This is my best try (based on Wrapper function in PowerShell: Pass remaining parameters) :
function Let
{
[CmdletBinding()]
Param([parameter(mandatory=$true, position=0)][string]$Option,
[parameter(mandatory=$false, position=1, ValueFromRemainingArguments=$true)]$Remaining)
Get #Remaining
}
function Get
{
[CmdletBinding()]
Param([parameter(mandatory=$false, position=0)][string]$OptionA,
[parameter(mandatory=$true, position=1)][string]$OptionB)
Write-Host $OptionA, $OptionB
}
But Let -Option c -OptionA 1
Prints -OptionA 1
which is obviously not what I intended.
If you don't require "advanced" function features from CmdletBinding(), then you can get away with using $args for this:
# simple function parameters are positional and named, but not mandatory
function let {
Param($OptionA,$OptionB)
write-host "OptionA=$OptionA"
write-host "OptionB=$OptionB"
get #args
}
function get {
Param($OptionC,$OptionD)
write-host "OptionC=$OptionC"
write-host "OptionD=$OptionD"
}
# not necessary to name or include parameters
let -OptionA A B -OptionC C D
OptionA=A
OptionB=B
OptionC=C
OptionD=D
# named parameters get assigned first, so the order is not too big a deal either
# these produce the same results as above:
let B -OptionA A D -OptionC C
let -OptionD D -OptionC C A B
Any named parameters will not get positionally assigned to let
Any additional parameters, named or otherwise, will be forwarded to get
That was hard!
For this you would need to add a bit of code in DynmaicParams and begin section of the function.
It might be possible to do it in an Attribute
function x{
[WrapperFor(y)]
Might do it Later.
function Get
{
[CmdLetBinding()]
Param([parameter(mandatory=$false, position=0)][string]$OptionA,
[parameter(mandatory=$false, position=1)][string]$OptionB)
Write-Host "opta",$OptionA
Write-Host "optb",$OptionB
}
function Let
{
[CmdletBinding()]
Param([parameter(mandatory=$true, position=0)][string]$Option,[parameter(mandatory=$false, position=0)][string]$OptionB)
DynamicParam {
AddWrapper -For "Get" -To "Let"
}
Begin {
$params = GetRestOfParams "Get" $PSBoundParameters
}
Process {
Get #params
}
}
Needed code:
using namespace System.Management.Automation
function Empt
{
[CmdletBinding()]
Param([parameter(mandatory=$true, position=0)][string]$aaaa)
1
}
function AddWrapper([parameter(mandatory=$true, position=0)][string]$For,[parameter(mandatory=$true, position=1)][string]$To)
{
$paramDictionary = [RuntimeDefinedParameterDictionary]::new()
$paramset= $(Get-Command $For).Parameters.Values | %{[System.Management.Automation.RuntimeDefinedParameter]::new($_.Name,$_.ParameterType,$_.Attributes)}
$paramsetlet= $(Get-Command empt).Parameters.Keys
$paramsetlet+= $(Get-Command $To).ScriptBlock.Ast.Body.ParamBlock.Parameters.Name | %{ $_.VariablePath.UserPath }
$paramset | %{ if ( -not ($paramsetlet -contains $_.Name) ) {$paramDictionary.Add($_.Name,$_)}}
return $paramDictionary
}
function GetRestOfParams($dst,$params)
{
$dstorgparams=$(Get-Command $dst).Parameters.Keys
$z= $params
$z.Keys | %{ if ( -not ($dstorgparams -contains $_) ) {$z.Remove($_)} } | Out-Null
return $z
}
I am writing a PowerShell module, the functions inside this module have some parameters which will be re-used across all functions. Rather than copy-pasting the function definition each time I add a new function, I would like to define them at the top like a script variable and then insert them into each function, giving me a single place to update if they need to be changed.
Looking at how dynamic parameters are defined it seems like I should be able to define an object of that type and then reference it in the function definitions, but I can't find anything online giving me the correct syntax to do this.
Using PowerShell version 7.2
$Script:ReUsedParameters = param(
[Parameter()]
[String]$Name,
[Parameter()]
[Int]$Id
)
Function New-Command {
Param ($ReUsedParameters)
Write-Output "Name: $Name, ID: $ID"
}
For the sake of answering, you can store the runtime parameters definitions in a script block and then call it & inside the function's dynamicparam block.
I do not think this is a good idea nor I recommend using this. All functions should have their own repeated param blocks if needed.
$reusedParameters = {
$paramDictionary = [System.Management.Automation.RuntimeDefinedParameterDictionary]::new()
# Since both parameters don't have any arguments (Mandatory, Position, ValueFromPipeline, etc..)
# you can use this one for both, otherwise, each dynamic parameter should have their own
# Parameter Declaration
[Parameter[]] $paramAttribute = [Parameter]::new()
$paramDictionary['Name'] = [System.Management.Automation.RuntimeDefinedParameter]::new('Name', [string], $paramAttribute)
$paramDictionary['Id'] = [System.Management.Automation.RuntimeDefinedParameter]::new('Id', [int], $paramAttribute)
return $paramDictionary
}
Function New-Command {
[CmdletBinding()] # `CmdletBinding` is Mandataroy here
param() # if the `param` block is empty
dynamicparam {
& $reusedParameters
}
end {
# Caveat: you can reference these parameters via $PSBoundParameters
# $Name and $Id are not part of the `param` block
# hence that wouldn't work here
"Name: {0}, ID: {1}" -f $PSBoundParameters['Name'], $PSBoundParameters['ID']
}
}
New-Command -Name asd -Id 123
As a declarative approach, you may turn the common parameters into class properties and have a single function parameter of the class type.
class MyReUsedParameters {
[String] $Name
[Int] $Id = 23
}
Function New-Command {
Param (
[MyReUsedParameters] $ReUsedParameters,
$AnotherParam
)
Write-Output "Name: $($ReUsedParameters.Name), ID: $($ReUsedParameters.ID)"
}
# Pass the common parameters as a hashtable which gets converted to
# MyReUsedParameters automatically.
New-Command -ReUsedParameters #{ Name = 'foo'; Id = 42 } -AnotherParam bar
# Alternatively pass the common parameters as a (typed) variable.
# PowerShell is able to deduce the argument name from the type.
$commonArgs = [MyReUsedParameters] #{ Name = 'Foo'; Id = 42 }
New-Command $commonArgs -AnotherParam bar
When passing a hashtable or PSCustomObject that has matching properties, it will automatically be converted to the class type.
You may even validate class properties similar to regular parameters. Most parameter validation attributes can be specified for class properties as well.
class MyReUsedParameters {
[ValidateNotNullOrEmpty()] [String] $Name
[Int] $Id = 23
# Constructor - required to apply validation
MyReUsedParameters( [Hashtable] $ht ) {
$this.Name = $ht.Name
$this.Id = $ht.Id
}
}
Function New-Command {
Param (
[Parameter(Mandatory)]
[MyReUsedParameters] $ReUsedParameters
)
Write-Output "Name: $($ReUsedParameters.Name), ID: $($ReUsedParameters.ID)"
}
# Causes an error (as expected), because Name property is missing
New-Command -ReUsedParameters #{ Id = 42 }
I'm trying to use the Windows PowerShell Classifier in FSRM on Server 2019. I need it to look for files that start with "~$" and classify them with a Yes or No property I created.
I would also be fine with a REGEX code as well.
This is what I have but it's not working:
# Global variables available:
# $ModuleDefinition (IFsrmPipelineModuleDefinition)
# $Rule (IFsrmClassificationRule)
# $PropertyDefinition (IFsrmPropertyDefinition)
#
# And (optionally) any parameters you provide in the Script parameters box below,
# i.e. "$a = 1; $b = 2" . The string you enter is treated as a script and executed so the
# variables you define become globally available
# optional function to specify when the behavior of this script was last modified
# if it consumes additional files. emit one value of type DateTime
#
# function LastModified
# {
# }
# required function that outputs a value to be assigned to the specified property for each file classified
# emitting no value is allowed, which causes no value to be assigned for the property
# emitting more than one value will result in errors during classification
# begin and end are optional; process is required
#
function GetPropertyValueToApply
{
# this parameter is of type IFsrmPropertyBag
# it also has an additional method, GetStream, which returns a IO.Stream object to use for
# reading the contents of the file. Make sure to close the stream after you are done reading
# from the file
param
(
[Parameter(Position = 0)] $PropertyBag
)
Process
{
$FileName = $_.Name
If($FileName -like "~$*")
{
$True
}
Else
{
$False
}
}
Consider two powershell functions:
function A {
params(
[Parameter()]$x,
[Parameter()]$y
)
Write-Host $x $y
}
function B {
params(
[Parameter()]$x,
[Parameter()]$z
)
Write-Host $x $z
}
I'd like to define a single parameter $x once (which could have fairly complex attributes that must be kept identical for both functions) and re-use it in both functions, so something like:
$x = {[Parameter()]$x}
function A {
params(
$x,
[Parameter()]$y
)
Write-Host $x $y
}
function B {
params(
$x,
[Parameter()]$z
)
Write-Host $x $z
}
(How) is this possible?
To reuse parameter declarations across functions - as requested in your question - see the following section.
To reuse parameter values (arguments) across functions, by way of presets (default value), see the bottom section.
In order to reuse parameter declarations - short of using design-time templating to generate source code - you need to to define a script block that creates a dynamic parameter that can be passed to the dynamicparam block of multiple advanced functions:
using namespace System.Management.Automation
# The script block that declares the dynamic parameter to be shared
# across functions.
$sharedDynParam = {
# Define the -x parameter dynamically.
$paramName = 'x'
$dict = [RuntimeDefinedParameterDictionary]::new()
$dict.Add(
$paramName,
[RuntimeDefinedParameter]::new(
$paramName,
[datetime], # Type the parameter [datetime]. for instance.
[ParameterAttribute] #{
Mandatory = $true # Make the parameter mandatory, for instance.
# ParameterSetName = 'default' # Assign it to a parameter set, if neeeded.
}
)
)
# Return the dictionary
return $dict
}
function A {
[CmdletBinding()]
param(
$y
)
# Assign the shared dynamic parameter.
dynamicparam { & $sharedDynParam }
# The use of `dynamicparam { ... }` requires use of an explicit
# `process { ... }` block (and optionally `begin { ... }` and
# `end { ... }`, as needed).
process {
# Note: A dynamic -x parameter cannot be accessed as $x
# Instead, it must be accessed via the $PSBoundParameters dictionary.
"[$($PSBoundParameters['x'])] - [$y]"
}
}
function B {
[CmdletBinding()]
param(
$z
)
# Assign the shared dynamic parameter.
dynamicparam { & $sharedDynParam }
process {
"[$($PSBoundParameters['x'])] - [$z]"
}
}
# Sample calls,
A -x '1970-01-01' -y yval
B -x '1970-01-02' -z zval
Output:
[01/01/1970 00:00:00] - [yval]
[01/02/1970 00:00:00] - [zval]
To preset the value of a parameter by a given name across commands, use the $PSDefaultParameterValues preference variable:
# Preset a parameter value for all commands ('*') that have
# an -x ('x') parameter.
$PSDefaultParameterValues = #{ '*:x' = [pscustomobject] #{ foo = 1; bar = 2 } }
function A {
[CmdletBinding()] # This makes the function an *advanced* one, which respects
# $PSDefaultParameterValues; similarly, at least one
# parameter-individual [Parameter()] attribute does the same.
param(
$x,
$y
)
"[$x] - [$y]"
}
function B {
[CmdletBinding()]
param(
$x,
$z
)
"[$x] - [$z]"
}
# Sample calls, without an -x argument, relying on
# $PSDefaultParameterValues to provide it automatically.
A -y yval
B -z zval
Output, showing that parameter -x was automatically bound via $PSDefaultParameterValues:
[#{foo=1; bar=2}] - [yval]
[#{foo=1; bar=2}] - [zval]
I have a function call implemented using Splatting.
$funtioncall= #{
Param1=$Param1;
Param2=$Param2;
Param3=$Param3;
Param4=$Param4;
Param5=$Param5;
}
function #functioncall
On a certain scenario i wish to add two more optional Parameters to the function call only if they are not null.
So i have $OptionalParam1 and $OptionalParam2
I currently have the below code to enable splatting as it will not allow nulls to be included in the Hash Table!
if(($OptionalParam1)-and($OptionalParam2))
{
$funtioncall= #{
Param1=$Param1;
Param2=$Param2;
Param3=$Param3;
Param4=$Param4;
Param5=$Param5;
OptionalParam1=$OptionalParam1;
OptionalParam2=$OptionalParam2;
}
}
else
{
$funtioncall= #{
Param1=$Param1;
Param2=$Param2;
Param3=$Param3;
Param4=$Param4;
Param5=$Param5;
}
}
function #functioncall
Is there a simpler way i can do this with Splatting?
This without splatting would be easier to implement and function call would look like below,( as i can have the parameter defined in the function to allow null )
function -Param1 $Param1 -Param2 $Param2 -Param3 $Param3 -Param4 $Param4 -Param5 $Param5 -OptionalParam1 $OptionalParam1 -OptionalParam2 $OptionalParam2
You should not have to change anything. $null is still a value so there is no reason to treat building of the variable $funtioncall differently at all
$param1 = "Awesome"
$OptionalParam1 = $null
$funtioncall= #{
Param1=$Param1;
OptionalParam1=$OptionalParam1;
}
So now the hashtable contains a null for OptionalParam1
Name Value
---- -----
OptionalParam1
Param1 Awesome
So as long as your function can handle to possibility of the param being null there will be no issue. I made a small function that displays those values.
This #funtioncall
Param1 is 'Awesome'
OptionalParam1 is ''