How to add items to a System.Collections.Generic.List object using PowerShell?

Question

I have an object that has a List<String> as a member. I tried adding items to this list in the following way:

$myObject.MyList.Add("News")
$myObject.MyList.Add("FAQ")
$myObject.MyList.Add("Events")

But when I check:

$myObject.MyList.Count

It returns 0. Is there a different way I should be doing this?

Snippit from my source code:

    [Personalizable(PersonalizationScope.Shared), WebBrowsable(false)]
    public List<String> SelectedTabs
    {
        get;
        set;
    }

Have you checked that $myObject.MyList is definitely a List and not null etc. and that it is implimented such that it gives the same list each time it's accessed. Not for example: public MyList {get{return new List<string>();}}//Always returns a new list — ForbesLindesay
– ForbesLindesay, Commented Dec 15, 2011 at 22:10
That smells like a sharepoint webpart - there's something else going on here, probably to do with the serialization of the property value. What's your context? — x0n
– x0n, Commented Dec 16, 2011 at 1:46

Shay Levy · Accepted Answer · 2011-12-16 07:21:01Z

5

I'm not a developer but maybe this is what you're looking for:

PS> $list = New-Object System.Collections.Generic.List[System.String]
PS> $list.Add("News")
PS> $list.Add("FAQ")
PS> $list.Add("Events")
PS> $list
News
FAQ
Events    

PS> $list.Count
3

answered Dec 16, 2011 at 7:21

Shay Levy

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Comments

manojlds · Accepted Answer · 2011-12-15 22:15:58Z

3

Works for me:

$source =@"
using System.Collections.Generic;
public class MyClass {
    public List<string> MyList;
    public MyClass(){
    MyList = new List<string>();
    }
}

"@

Add-Type -TypeDefinition $source -Language CSharpVersion3

$myObject = new-object MyClass

$myObject.MyList.Add("test");

$myObject.MyList.Count

answered Dec 15, 2011 at 22:15

manojlds

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2 Comments

Abe Miessler Over a year ago

Would it make a difference that I am using [reflection.assembly]::Load("MyAssembly, Version=1.0.0.0, Culture=neutral, PublicKeyToken=13da1371f01433e6e") instead of Add-Type?

manojlds Over a year ago

@AbeMiessler - It shouldn't. Do you have sample code for you assembly?

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