Question

I have a function defined as follows:

function Get-LatestProjects
{
    [CmdletBinding()]
    Param
    (
        [Parameter(ValueFromPipeline = $true, Position = 0)]
        [Company.Project.Entities.Project[]] $Projects
    )
    Begin {}
    Process
    {
        ...
    }
    End {}
}

I’m calling this function from C# and the parameter in the code is an array of that type, but I’m getting this error:

Cannot process argument transformation on parameter ‘Projects’. Cannot convert the “Company.Project.Entities.Project[]” value of type “Company.Project.Entities.Project[]” to type “Company.Project.Entities.Project”.

The C# code that makes the call:

var script = @". \\server01\Runspace.ps1; Get-LatestProjects $args";
var args = _pmRepository.GetAllProjects().ToArray(); // GetAllProjects returns List<Project>

using (Runspace runSpace = RunspaceFactory.CreateRunspace())
{
    runSpace.Open();
    var ps = PowerShell.Create();
    ps.Runspace = runSpace;
    ps.AddScript(script);
    ps.AddArgument(args);

    Collection<PSObject> results = ps.Invoke();
    ...
}

Do I need to do any conversion of the objects before I pass them to the powershell function? Or can I not add a type constraint in the powershell function for the $Projects parameter?

Answer 1

It looks like _pmRepository.GetAllProjects() return only one project. Can’t you just declare $Projects without type and use $Projects.gettype to have a look to the type.

function Get-LatestProjects
{
    [CmdletBinding()]
    Param
    (
        [Parameter(ValueFromPipeline = $true, Position = 0)]
        $Projects
    )
    Begin {
       #Set-Content -path c:\temp\debug.txt -value $Projects.Gettype()
       $projects | get-member -force | out-file -filepath c:\temp\debug.txt
    }
    Process
    {
        for ($i=0 ; $i -le $projects.count ; $i++)
        {
           $projects[$i].State  | out-file  -filepath c:\temp\debug.txt -append
        }
    }
    End {}
}

—-Edited——

You can avoid your array to be wraped into another array by writting.

var script = @". \\server01\Runspace.ps1; Get-LatestProjects $args[0]";