How to create a PowerShell script that accepts one or more SPWebApplication and use it in an expression?

Question

I'm trying to create a custom function that can uninstall and reinstall any SharePoint solution.

Some solutions requires the -GACDeployment switch, some requires the -AllWebApplications and some requires the -WebApplication switch.

How can I properly handle this multiple combinations?

By now, I have a function that works well with the two first possibilities (Gac and all web applications). But I having some troubles to make the multiple web application possibles.

Here is a sample of how the function should be called:

 # Already working :
 Update-SPSolutionWithCompleteReinstall .\SolutionwithGac.wsp
 Update-SPSolutionWithCompleteReinstall .\SolutionwithWebRes.wsp -AllWebApplications
 Update-SPSolutionWithCompleteReinstall .\SolutionwithWebRes.wsp -WebApplications "http://app1"
 $webApp = Get-SPWebApplication "http://app1"
 Update-SPSolutionWithCompleteReinstall .\SolutionwithWebRes.wsp -WebApplications $webApp

 # Not working :
 Update-SPSolutionWithCompleteReinstall .\SolutionwithWebRes.wsp -WebApplications "http://app1","http://app2"
 $webApp1 = Get-SPWebApplication "http://app1"
 $webApp2 = Get-SPWebApplication "http://app2"
 Update-SPSolutionWithCompleteReinstall .\SolutionwithWebRes.wsp -WebApplications $webApp1,$webApp2

And here is the function itself :

function Update-SPSolutionWithCompleteReinstall
{
    [CmdLetBinding(DefaultParametersetName="NoWebApplication")]
    param(
        [Parameter(Mandatory=$true,ParameterSetName="NoWebApplication", Position=0)]
        [Parameter(Mandatory=$true,ParameterSetName="WebApplications", Position=0)]
        [Parameter(Mandatory=$true,ParameterSetName="AllWebApplications", Position=0)]
        [string]$filePath,
        [Parameter(ParameterSetName="AllWebApplications", Position=1)]
        [switch]$AllWebApplications,
        [Parameter(ParameterSetName="WebApplications", Position=1)]
        [Microsoft.SharePoint.PowerShell.SPWebApplicationPipeBind]$WebApplications
    )
    $filePath = Resolve-Path $filePath
    $wspFileName = Split-Path -leaf $filePath

    $currentSol = Get-SPSolution | ? { $_.Name -match $wspFileName }

    # 1. Uninstall the solution
    if($currentSol)
    {
        Write-Host "The solution $($currentSol.Name) has been found. Uninstalling it"
        if($currentSol.ContainsWebApplicationResource)
        {
            Uninstall-SPSolution $currentSol -AllWebApplications -Confirm:$false
        }
        else
        {
            Uninstall-SPSolution $currentSol -Confirm:$false            
        }
        Wait-SPSolutionDeploymentJobToFinish $currentSol.Name

        Write-Host "Remove $($currentSol.Name) from the solution store"
        Remove-SPSolution $currentSol -Confirm:$false       
    }

    # 2. install and deploy the new solution
    Write-Host "Adding the solution $filePath"
    $newSol = Add-SPSolution -LiteralPath $filePath

    $expr = 'Install-SPSolution $newSol'

    if($newSol.ContainsWebApplicationResource)
    {
        switch ($PsCmdlet.ParameterSetName) 
        {
            "AllWebApplications" {
                $expr += " -AllWebApplications"
            }
            "WebApplications" {
                $expr += " -WebApplication $($WebApplications.Read().Url)"
            }
        }
    }
    if($newSol.ContainsGlobalAssembly)
    {
        $expr += ' -GACDeployment'
    }

    Write-Host "Install the solution $filePath"
    Invoke-Expression -Command $expr 

    Wait-SPSolutionDeploymentJobToFinish $newSol.Name

}

The specific part of the function where the trouble is located, is where I'm building a custom expression to be invoked.

Answer 1

Basically handle it how you would when presented this in other languages, pass an array for the site parameter.

For format in powershell for this is:

[string[]]$stringArray

$stringArray = @("site1","site2")

That way you can handle how many you send and/or do another method depending what you pass.

[update]

There isn't a type you can pass in to handle this without something ugly as in:

$webApp1 = Get-SPWebApplication "http://app1"
$webApp2 = Get-SPWebApplication "http://app2"
$WebAppArray = @($webApp1, $webApp2);
Update-SPSolutionWithCompleteReinstall .\SolutionwithWebRes.wsp -WebApplications (,$WebAppArray)

I would be really tempted to handle the innards of this function differently, so you can consume a simpler string input. Another parameter set to consume this in a simpler format?

The reason you couldn't do it another way afaik is that all the variables passed after the parameter count get put into the final variable, and powershell parameters as cool as they are won't consume the input in the way you are expecting.

WebApplications now would accept multiple string inputs and convert that after the params to the required type.

// Post processing here
switch ($PsCmdlet.ParameterSetName)
{
    "WebApplications" { //code to handle here }
    "NoWebApplication" { ... }
    "AllWebApplications { ... }
}

// All common code here

Best I can come up with.