CODEWITHSUNDEEP
powershellgenericspowershell-5.0
Michael Sync
Michael Sync

Reputation: 5004

Using Generic.List with custom type as a return type for function is not working

Edited #3.

I managed to get it working. I need to load all dependencies in the correct order in the main script file. not from the class file so I will vote it to close this post.

I am using powershell 5.0 on Windows 10. Using List (e.g. $list = New-Object System.Collections.Generic.List``1[CustomClass]) works in most of the cases. But got the error when I used it as a return type.

The code below doesn't work. 

class CustomClass1 {

   [System.Collections.Generic.List``1[CustomClass]]GetColumns([string]$tableType){
     $list = New-Object System.Collections.Generic.List``1[CustomClass]
     return $list
  }
}

Edited: #1

I tried this code below but didn't work as well.

[System.Collections.Generic.List``1[CustomClass]]GetColumns([string]$tableType) {
        $list = New-Object System.Collections.Generic.List``1[CustomClass]
        $c= New-Object CustomClass
        $list.Add($c)

        return ,$list
    }

Edited: #2

I push my test scripts in this repo https://github.com/michaelsync/powershell-scripts/tree/master/p5Class

CustomClass.ps1

class CustomClass {
  [string]$ColumnName
}

CustomClass1.ps1

. ".\CustomClass.ps1" 

class CustomClass1 {

  [System.Collections.Generic.List``1[CustomClass]]GetColumns(){

     $list = New-Object System.Collections.Generic.List``1[CustomClass]
     $c = New-Object CustomClass
     $list.Add($c)

     return $list
  }
}

Test.ps1

. ".\CustomClass1.ps1" 

$c1 = New-Object CustomClass1
$c1.GetColumns()

If I put all classes in one file, it works. I think it has something to do with the way the ps1 files are being loaded. (Thanks @jesse for the tip. )

But if I use normal type such as string, int and etc, it works. 

class CustomClass1 {

   [System.Collections.Generic.List``1[string]]GetColumns([string]$tableType){
     $list = New-Object System.Collections.Generic.List``1[string]
     return $list
  }
}

It also works when I assign the generic list with custom class. 

$list = New-Object System.Collections.Generic.List``1[CustomClass]
$c = New-Object CustomClass
$list.Add($c)

Is that the known issue that we can't return the generic list with custom class type?

Upvotes: 1

Views: 2404

Answers (1)

jessehouwing
jessehouwing

Reputation: 114887

Your error "Unable to find type [CustomType]" indicates that there is an issue in the order in which types are loaded, or that you've missed loading a dependency (be it a script or an assembly) completely.

Check that before your functions are used, all the scripts and assemblies are loaded.

Upvotes: 1

Related Questions