How to correctly marshal VB-Script arrays to and from a COM component written in C#

Question

I\'m building a COM object in C# (.Net 4.0) to be used in an classic asp site. Now I\'d like to know what\'s the proper way to marshal VB-Script arrays (single and multidime

Answer 1

A bit late, but in case someone needs this in the future:

I managed to pass an ArrayList of Hashtables to Classic ASP. It seems that types of the namespace System.Collections can be passed, System.Collections.Generic can not.

.cs-File:

using System;
using System.Runtime.InteropServices;
using System.Collections;

namespace Test
{
    [ComVisible(true)]
    [Guid("D3A3F3E7-F1A9-4E91-8D7B-D9E19CF38165")]
    public interface iDemo
    {
        [return: MarshalAs(UnmanagedType.Struct, SafeArraySubType = VarEnum.VT_ARRAY)]
        ArrayList DemoMethod();
    }


    [ProgId("Test.Demo")]
    [ClassInterface(ClassInterfaceType.None)]
    [Guid("F53257DD-9275-4D6C-A758-EFF6932FF8B2")]
    [ComVisible(true)]
    public class Demo : iDemo
    {
        [ComVisible(true)]
        public ArrayList DemoMethod()
        {
            ArrayList Results = new ArrayList();

            for (int i = 0; i < 5; i++)
            {
                Hashtable table = new Hashtable();
                table.Add("Text", "Test"+i);
                table.Add("Number", i);
                Results.Add(table);
            }
            return Results;
        }
    }
}

.asp-File:

<%
set test = server.createObject("Test.Demo")
set results = test.DemoMethod()
response.write "Results: " & results.count & "

"
for each result in results
    response.write result("Text") & "
"
    response.write result("Number") & "

"
next
%>

Output:

Results: 5

Test0
0

Test1
1

Test2
2

Test3
3

Test4
4

This is pretty convenient if you have to pass a lot of data from C# to Classic ASP (Should work in VB Script too, but not tested), as you can loop through objects with any attributes. Also didn't test the other way around, because I only needed to pass data from C# to Classic ASP.