Tag Archives: parameters

Get the Total Parameter Count

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Update: There was an update to this post on May 29, 2018. See below.

It’s been a littler longer than normal for me to have not written. My entire week last week didn’t include a post; it’s so weird. Well, I’m taking a quick minute — seriously — to discuss something I wanted to do recently.

In a new project I’m on, I wanted to know how many parameters a function has from inside the function itself. I didn’t want to know how many parameter were used when the function was invoked. Had I, I would’ve used $PSBoundParameters. Again, I wanted to know how many parameter(s) the function had, whether they were used or not.

I’ll tell you what I opted to do. On that note, do however, let me know if you come up with a better idea. I didn’t give this a ton of time. That said, it doesn’t even have to be better; I’d still like to hear about it. For me, I opted to execute a Get-Help command against the function, from inside the function. I’m making this a quick post, so let’s jump to some code.

Function Check-ParameterCount {
    [CmdletBinding()]
    Param (
        [Parameter()]
        [string]$Param01,

        [Parameter()]
        [string]$Param02,

        [Parameter()]
        [ValidateSet('Source','Destination')]
        [string]$Param03
    )

    $ParameterCount = (Get-Help -Name Check-ParameterCount).Parameters.Parameter.Count
    "There are $ParameterCount possible parameter(s) in this function not including the common parameters."
}

PS > Check-ParameterCount
There are 3 possible parameter(s) in this function.

The next example is the same example as above, however, we’ve removed the third parameter. Sure enough, the value is now two. As you may have noticed, Get-Help gets its parameter count from the actual parameter(s) themselves. Neither function has any comment-based help. Therefore, we can determine that it doesn’t use any static help we might include in regard to the parameter(s).

Function Check-ParameterCount {
    [CmdletBinding()]
    Param (
        [Parameter()]
        [string]$Param01,

        [Parameter()]
        [string]$Param02
    )

    $ParameterCount = (Get-Help -Name Check-ParameterCount).Parameters.Parameter.Count
    "There are $ParameterCount possible parameter(s) in this function not including the common parameters."
}

PS > Check-ParameterCount
There are 2 possible parameter(s) in this function.

That was it. Again, let me know if there’s a better way.

Update: I had a thought. Because my function uses the CmdletBinding attribute, it’s possible that my function can have more than the number of parameters returned by Get-Help. Therefore, I’ve only slightly modified the above strings my function returns. It was “There are $ParameterCount possible parameter(s) in this function.”, and now it’s “There are $ParameterCount possible parameter(s) in this function not including the common parameters.” Now, it indicates it returns X number of parameters, not to include the command parameters.

PS > Check-ParameterCount
There are 2 possible parameter(s) in this function not including the common parameters.

Twitter Reply – Finding Parameters that Include a Default Value

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Adam Bertram, an active PowerShell MVP, wrote on Twitter about the need to determine which parameters have default values. I can’t resist a challenge, and so I very quickly wrote out the function below. No guarantees, but maybe it’ll help.

Update: It turns out that the function that Adam was working with, didn’t include help. Shame. Even so, this small script may assist someone to pull back the parameters that have default values.

Get-Help Get-Service |
    Select-Object -ExpandProperty parameters |
    Select-Object -ExpandProperty parameter | 

    Foreach {
        If ($_.DefaultValue -ne '') {
            $Object = [pscustomobject]@{
                Name = $_.Name
                Default =$_.DefaultValue
            }
        Write-Output -InputObject $Object
        }
    }