InvalidCastException in ICollection.CopyTo when using a typed collection as DataSource (.NET/C#)

Hi all

When I try to bind e.g. a combobox to a typed collection, I get an InvalidCastException. I've generated typed collections using ArrayList.cst and CSVector.cst but both showed the same behaviour.

Can anyone help me? What am I missing?

Cheers
Dejan

Thanks for the bug report -- I don't use data-bound control so I would never have noticed.

Could you please post a or e-mail me a minimal code sample that reproduces this bug? No need to attach the generated collection, of course; just tell me the data type you're using.

Thanks, Chris

Ok, here we go.
Create a simple test class as:

public class Test
{
public string Text { get { return "TEST"; } }
public Test()
{
}
}

Next create a typed collection using ArrayList.cst. Let's call it TestCollection.
Then on a form try:

TestCollection c = new TestCollection();
c.Add(new Test());
comboBox1.DataSource = c;
comboBox1.DisplayMember = "Text";

This will result in an InvalidCastException in ICollection.CopyTo(Array array, int arrayIndex).
Copying the array manually will work. E.g. the following code works without throwing an exception:

TestCollection c = new TestCollection();
c.Add(new Test());
Test[] arr = new Test[c.Count];
c.CopyTo(arr);
comboBox1.DataSource = arr;
comboBox1.DisplayMember = "Text";

Note that a the CSVector.cst template displays the same behaviour.

Thank you very much,
Dejan

Thanks for the sample code! I suspect there's some implicit assumption in the bowels of Windows.Forms that may be to blame here. I'll write up a test program and will report back when I know what happens.

Thanks a lot! It works well with the newest version.

Cheers, Dejan