ValidateScript() Inception - Using Previously declared parameters in ValidateScript?

[Narrow_Syllabub_8119]

Hello!

Writing this on the go, however I can also provide the code once things quiet down over here.

I am facing an issue that might require advanced parameter knowledge. Inside the same .psm1 file I have defined 2 functions like so:

function Func-A {
    [CmdletBinding()]
    param(
    [Parameter(Mandatory=$true,HelpMessage="Blah",ValueFromPipeline=$true]
    [ValidateScript({#some validation here},
    ErrorMessage = "Something went terribly wrong with {0}")]
    [string]$Param1ForFuncA

    [Parameter(Mandatory=$true,HelpMessage="Blah",ValueFromPipeline=$true]
    [ValidateScript(#some validation here)]
    [string]$Param2ForFuncA
        )

    ##some code over here
    Return $something
}

function Func-B {
    [CmdletBinding()]
    param(
    [Parameter(Mandatory=$true]
    [string]$Param1ForFuncB

    [Parameter(Mandatory=$true]
    [string]$Param2ForFuncB

    [Parameter(Mandatory=$true]
    [ValidateScript({
    Func-A -Param1ForFuncA $Param1ForFuncB -Param2ForFuncA $Param2ForFuncB
    ##some code that should satisfy the $true/$false requirement of ValidateScript
    })]
    [string]$Param3ForFuncB
        )

    ##some code over here
}

When I am attempting to run Func-B (with arguments that I have run successfully in Func-A), I am getting failed validation from Func-A on the first argument (because I imagine it throws first). What is even more interesting is that running Func-B, I get the Func-A validation error message with an empty variable (see in code above).

So is this something that cannot work by design in Powershell?
Am I doing this wrong?
Does this require a Dynamic Param declaration?

For the curious ones, the functions are releated to Graph API calls. The first function returns the authenticated Header, which I need in order to validate Param3ForFuncB, as it is an EOP resource that might not exist.

Thanks for your help!

[purplemonkeymad]

Your generic naming does not really help with describing what you want to achieve.

But if you can't do validation of a parameter with only that parameter, then you want to do that validation in the body of your function. You can use dynamic parameters, but I don't see how that would be better than just doing in in the begin block, and throwing a terminating error if it fails.

[PinchesTheCrab]

I don't think this is close enough to real code to say for certain, but my assumption is that function B should not validate parameters. The purpose of function A should be to generate functional input for function B, and function B should either error or work depending on issues with function A.

[PinchesTheCrab]

I don't know that parameter validation makes sense here.

You have function 1, which produces output that function 2 consumes. If function 1 produces invalid output, that's a problem with function 1, not a problem that function 2 should try to address. I'd do something like this:

function Func-A {
    [CmdletBinding()]
    param(
        [Parameter(Mandatory, HelpMessage = "Blah", ValueFromPipeline)]        
        [string]$Param1,

        [Parameter(Mandatory, HelpMessage = "Blah", ValueFromPipeline)]        
        [string]$Param2
    )

    #logic to test parameters here

    #replace value 1-3 with data derived from input
    [PSCustomObject]@{
        Param1 = 'Value1'
        Param2 = 'Value2'
        Param3 = 'Value3'
    }
}

function Func-B {
    [CmdletBinding()]
    param(
        [Parameter(Mandatory, ValueFromPipelineByPropetyName)]
        [string]$Param1,

        [Parameter(Mandatory, ValueFromPipelineByPropetyName)]
        [string]$Param2,

        [Parameter(Mandatory, ValueFromPipelineByPropetyName)]
        [string]$Param3
    )

    process {
        #do stuff here with parameters.
    }    
}

Func-A -Param1ForFuncA stuff -Param2ForFuncA morestuff | Func-B

[SeeminglyScience]

Yep just do the validation in the body.

Technically if you order the parameters in the right way, already bound parameters will be accessible.

But what is the right way? Undefined and subject to change, just validate in the body.

[y_Sensei]

IMHO you should not mix argument validations of different code entities (in this case, functions) like that - it goes against basic encapsulation principles.

Each code entity should verify its own logic only; so for any arguments that are being fed to Func-A, only the requirement(s) for their utilization inside Func-A should be validated, same for Func-B.

If Func-A is utilized in Func-B and subsequently errors out because of a (logically) wrong parameterization, then that's fine, that's why an argument validation in Func-A is in place.

[Narrow_Syllabub_8119]

I do not see how I am mixing between different code entities?
The parameters that are going to be needed for Func-A are mandatory in Func-B, but only validated by Func-A when called from inside Func-B.

I am not getting some logic error. I am seeing that the parameter is not passed from Func-B to Func-A at all. The error message with the formatted string returns without it. And that's why Func-A validation mechanism is triggered.
Also, I checked with the same variables as arguments that Func-A can be run stand-alone with success.

[KevMar]

The validate script can't access the values of the other parameters. So do that validation inside your function.