如何将对象集合从VB6传递到.NET？

Question

I need to pass a collection of key/value pairs of strings from VB6 to .NET. In VB6 code they exist in a native collection. But I am not sure what I can reference in my .NET project to be able to accept a parameter of type Collection in one of my methods.

I tried adding a reference to Visual Basic for Applications but got back "A reference to 'Visual Basic For Applications' could not be added."

Am I going about it the wrong way?

Answer 1

You could use something like this in c#:

[Guid("fb5e929a-2f8b-481e-9516-97edf5099df4")]
[ComVisible(true)]
public interface myInterface{
public void addObject(string key, string value);
}

And in your class, you could have this:

private collection
public addObject(string key, string value)
{
collection.Add(key, value);
}

This should allow you to call addObject in vb6 and passing your data. Then .net will add it to a collection, so instead of passing your whole collection from vb6 to .net, you pass them one by one.

You can read more about the GUID here.

More info about COM with an exemple of code between vb6 and c# here.

Answer 2

Rather than using COM , I have found it far simpler to just serialize my data as JSON and send it over the Interop chasm as plain text. I resisted it at first, but it is now my go-to solution. Give it a try if the "proper" solutions prove frustrating.

Answer 3

Try passing it to .NET by making a HashTable in Visual Basic 6.0:

Set dictionary = Server.CreateObject("System.Collections.HashTable")
With dictionary
    For i = 1 To 100
        .Add Chr(i), "some text value"
    Next
End With

Then in a C# or VB.NET COM exposed class

public string LoadHashTable(Object tDict)
{
   return String.Format("Type : \"{0}\", Count : {1}", ((Hashtable)tDict).GetType().ToString(), ((Hashtable)tDict).Count);
}

An example of a COM exposed class is in Stack Overflow question Building a COM interop library for ASP Classic using 4.0 framework and Visual Studio 2010

Remember to register it in both x86 and x64:

%windir%\Microsoft.NET\Framework\v4.0.30319\regasm MyThing.dll /tlb:MyThing.tlb /codebase MyThing

%windir%\Microsoft.NET\Framework64\v4.0.30319\regasm MyThing.dll /tlb:MyThing.tlb /codebase MyThing