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Can a PowerShell function handle multiple input types?
(1 answer)
Closed 1 year ago.
I have a script that deals with Active Directory User objects (Microsoft.ActiveDirectory.Management.ADUser). I explicitly list the type in the function that processes these objects:
function Write-ADUser {
param (
[Microsoft.ActiveDirectory.Management.ADUser]$user
)
(...)
I also want this function to be able to take objects from remote sessions. The challenge is that objects returned from remote sessions are of the deserialized variety:
C:\> icm -session $sess { get-aduser -identity testuser -credential $cred } | gm
TypeName: Deserialized.Microsoft.ActiveDirectory.Management.ADUser
Is there a way to have my function param block accept either the "live" object or the deserialized variant? My function doesn't need to use methods - the deserialized variant has (or can be made to have) what I need.
The parameter sets idea was interesting and a helpful lead. After reviewing the documentation, this is the best option I could come up with:
function Write-ADUser {
[CmdletBinding()]
param (
[Parameter(Mandatory=$true, Position=0, ValueFromPipeline=$true)]
[ValidateScript({
if ($_.GetType().Name -notin #('ADUser', 'PSObject')) {
throw ("Error: Invalid type ````{0}'' - expecting ADUser.") -f $_.GetType().Name
} else {
$true
}
})]
$user
)
...
One other comment. When looking into parameter sets I kept getting an error about ADUser. However, upon further digging I believe that error is because the Microsoft Active Directory PowerShell module isn't installed on my test computer. Therefore, the 'ADUser' type isn't defined. Because I want this script to run on computers that don't necessarily have the ADModule I am using the above logic. However, if I could guarantee that ADModule was present then I think parameter sets would be the way to go.
Apologies for not providing clearer requirements. I'm still learning PowerShell...
Note - updated based on feedback from #zett42
Related
I was able to reproduce this in a more generic way, and the issue is different than originally presented. I have rewritten this question to reflect the issue experienced along with a generic reproducible example.
I have a cmdlet that sometimes produces no output when it doesn't find any data to return. However, I use this function to pass information to another cmdlet which accepts pipeline input via way of the ValueFromPipelineByPropertyName attribute. When there is an actual object being passed down the pipeline, everything works as expected, including parameter validation checks. However, if the passed object is $null, then parameter validation gets skipped. Note that this is not reproduceable when simply passing $null down the pipeline; I've only been able to reproduce this when emitting no output down the pipeline.
I've been able to reproduce this generically. The parameters are defined with the same attributes as my real code:
Function Get-InfoTest {
Param(
[switch]$ReturnNothing
)
if( !$ReturnNothing ) {
[PSCustomObject]#{
Name = 'Bender'
Age = [int]::MaxValue
}
}
}
Function Invoke-InfoTest {
Param(
[Parameter(Mandatory, ValueFromPipelineByPropertyName)]
[string]$Name,
[Parameter(Mandatory, ValueFromPipelineByPropertyName)]
[int]$Age
)
Write-Host "Hello, $Name. I see you are $Age years old."
}
# With valid object
Get-InfoTest | Invoke-InfoTest
# Correct behavior when $null is directly passed into the cmdlet, throws error
$null | Invoke-InfoTest
# With returned null object, should throw an error but executes with an incorrect result
Get-InfoTest -ReturnNothing | Invoke-InfoTest
What is going on here? While it's not difficult to write null-or-whitespace checks in the function body, this is the point of the Mandatory parameter option as well as the Validate* parameter attributes. In my real code, I now need to write null-or-whitespace checks for several parameters which already have validation attributes set. As stated in the code comments, passing $null into the target cmdlet results in the correct error being thrown, but no output produced from a function results in the function executing as if everything was provided correctly.
If you don't define begin/process/end blocks, functions bodies default to an end block. However, putting the function body in an explicit process block results in the correct behavior:
The following modification to Invoke-InfoTest results in the sample code working correctly for all cases:
Function Invoke-InfoTest {
Param(
[Parameter(Mandatory, ValueFromPipelineByPropertyName)]
[string]$Name,
[Parameter(Mandatory, ValueFromPipelineByPropertyName)]
[int]$Age
)
# Note that I've wrapped this in a process block
process {
Write-Host "Hello, $Name. I see you are $Age years old."
}
}
This works because as stated above, functions default to an end block if unspecified. However, the end and begin blocks are executed regardless of the pipeline object being input. process only gets executed when there is data passed in. Defining the code using the pipeline variables inside of a process block effectively stops the code using the missing data from being executed, which seems to be by design.
Thanks to #SantiagoSquarzon in the comments for helping me realize the actual problem.
I am trying to setup dynamic parameters that vary depending on if you are adding or modifying/removing a drone. Ex: If you are adding a drone you would need its IP/Name/Location.. To remove the drone you would only need its name. I have tried looking online and try various examples I've seen but I am completely stuck here. Any help to steer me in the right direction would be appreciated. I am somewhat new to powershell. Here's what I have.
[CmdletBinding(SupportsShouldProcess=$True)]
Param( [Parameter(Mandatory=$true,
HelpMessage = "Add remove or Modify a drone?")]
[ValidateSet("Add", "Remove", "Modify")]
[String]$Action)
DynamicParam{
if ($action = "Add"){
Param( [Parameter(Mandatory)]
[ValidateSet("NorthAmerica", "SouthAmerica", "NorthernEurope","UK", "CEE", "FRMALU", "SouthernEurope", "AsiaPacific")]
[String]$curRegion,
[Parameter(Mandatory)]
[IPAddress]$ip,
[Parameter(Mandatory)]
[String]$droneName)
}
if ($action = "Remove"){
Param(
[Parameter(Mandatory)]
[string]$droneRemoveName)
}
}
Consider driving your parameter constraints with named Parameter Sets instead. I'm suggesting this because dynamic parameters don't work quite like you think they do, but named parameter sets are an easier way to solve your problem. In case you're interested, here's a blog post explaining how to use dynamic parameters and it winds up being pretty manual parameter handling.
You can add a parameter to more than one parameter set depending on the contexts in which each parameter is required. Instead of using -Action ACTION as a driver for a dynamic parameter, use a [switch] instead, such as -Add and -Remove, and have each switch part of its own parameter set. For example, when defining your parameters, it may look something like this:
Param(
[Parameter(ParameterSetName='Remove')]
[switch]$Remove,
[Parameter(ParameterSetName='Add')]
[switch]$Add,
[Parameter(ParameterSetName='Remove', Mandatory)]
[Parameter(ParameterSetName='Add', Mandatory)]
[string]$IPAddress
)
In this example, -IPAddress is valid when you use the -Add or -Remove switch, but won't be relavant outside of this context. Of course, if a parameter should only be valid for a certain parameter set, don't define it under more than one parameter set name.
If you want to make sure at least one "action" switch is defined before executing, you can check that one of those parameters was used when invoking the cmdlet by checking $PSBoundParameters:
('Add' -in $PSBoundParameters.Keys) -Or ('Remove' -in $PSBoundParameters.Keys)
Good morning, everyone,
I have a problem in retrieving information from SharePoint groups. I do it in a workflow, first I get the list of all groups and then I use it in a foreach-parallel to list the members of these groups.
The problem is that the connection doesn't seem to be maintaining and my query doesn't recover all the groups.
Here is a piece of the code:
workflow GetGroup {
param(
[Parameter(Mandatory)]
[String]$SPOSite,
[System.Management.Automation.PSCredential]$SPOCreds
)
$KeepAlive = Connect-PnPOnline -Url $SPOSite -Credentials $SPOCreds -ReturnConnection
$GetGroups = Get-PnPGroup
ForEach -Parallel -ThrottleLimit 512 ($Group in $GetGroups)
{
$GroupName = $Group.LoginName
$Users = Get-PnPGroupMembers -Identity $groupName -Connection $workFlow:KeepAlive
}
}
GetGroup -SPOSite "https://xxx.sharepoint.com/sites/xx -SPOCreds (Get-Credential)
The expected result would be an array initialized at the beginning of the workflow with a PSCustomObject object that is added to our array. This table is made up of 3 things: The name of the group, the names of the people in that group, the emails of the people.
Unfortunately the table is only partially generated because a workflow here is the error I find nothing on the subject:
Impossible to link the "Connection" parameter. Impossible to convert the value "SharePointPnP.PowerShell.Commands.Base.SPOnlineConnection" of the type "SharePointPnP.PowerShell.Commands.
Deserialized.SharePointPnPnP.PowerShell.Commands.Base.SPOnlineConnection"
Thank you for your help.
I ran into the same error in a similar scenario, and this article helped me. Workflow is converting the Connection object ($KeepAlive in your case) to a deserialized format, and so the other cmdlet doesn't accept it. You will just have to wrap those cmdlets with InlineScript, or use a PowerShell script runbook instead of a PowerShell workflow runbook.
I understand from this answer that when you have default parameters and multiple parameter sets in a Powershell function, the default parameter values will be instantiated even if the parameter set in use is not the one in which they are inserted.
Is there a way to avoid this?
For example, in the function below, assuming that there is a really expensive calculation used to compute the default value of $FirstParameter, I would like to avoid using it when it is not necessary:
function PrintStuff {
[CmdletBinding(DefaultParameterSetName='FirstSet')]
Param(
[Parameter(ParameterSetName='FirstSet')]
[String]$FirstParameter=(ReallyExpensiveFunction),
[Parameter(ParameterSetName='SecondSet')]
[String]$SecondParameter
)
if (-not ($FirstParameter -eq $null)) {Write-Host $FirstParameter}
Write-Host "$($PSCmdlet.ParameterSetName)"
}
function ReallyExpensiveFunction {
# Very expensive calculation
"I Am First"
}
However, at the moment running it would still give me the results below:
PS C:\> PrintStuff
# I Am First
# FirstSet
PS C:\> PrintStuff -SecondParameter "don't print this"
# I Am First
# SecondSet
As per above, when SecondSet is used $FirstParameter is still being defined. Is there a way to get only SecondSet printed when the second parameter set is used?
Bear in mind, I am looking to find out if there is a solution which would allow me to keep ReallyExpensiveFunction as the default value for $FirstParameter, and avoid solutions which would involve transferring the logic to the body of the function, such as:
...
Param(
[Parameter(ParameterSetName='FirstSet')]
[String]$FirstParameter,
...
)
if ($PSCmdlet.ParameterSetName -eq 'FirstSet' -and ($FirstParameter -eq '')) {
$FirstParameter = ReallyExpensiveFunction
}
...
Sorry if the pitch is too specific, but I am curious to find out if this is possible.
Unfortunately, the answer is no. ParameterSet allows to present a simpler interface to user for complex argument sets by filtering out the non-relevant ones. However, PowerShell goes through each parameter, whether it is in the selected parameterset or not and assign the default value to the parameter, if you specify one. So, simply put in the context of your question, ParameterSet may be thought as just a filter for presentation.
I'm new to powershell and my first module is for simply adding users to the local admin group on remote computers. It looks like:
function AddAdmin {
[CmdletBinding()]
Param(
[Parameter (Mandatory=$True,ValueFromPipeline=$True,Position=1) ]
[string[]]$Computer,
[Parameter (Mandatory=$True,ValueFromPipeline=$True,Position=2) ]
[string]$username
)
$Domain = "the domain"
$Group = [ADSI]"WinNT://$Computer/Administrators,group"
$Usertoadd = [ADSI]"WinNT://$Domain/$username,user"
$Group.Add($Usertoadd.Path)
}
so I can just type addadmin computername username and it gets added. I want to do the same for groups, the problem I'm having is figuring out how to set a parameter that has multiple values/words. For example let's say I want to add a group called Executive Team to local admins. addadmin computername executive team doesn't work - it only picks up executive as the value.
Googled quite a bit and can't seem to figure this out, I'm sure I'm missing something simple.
You just have to put the multiple words value into double quotes :
addadmin computername "executive team"
Positions start at 0, just FYI, and while JPBlanc's answer is correct (and honestly better from a technical standpoint) you should be able to add this to your Parameter list for the User Name to get the same results without having to put them in quotes.
ValueFromRemainingArguments = $true