Ignore Nested Types with DataContractSerializer

Question

I have a class in C# that I am trying to serialize using a DataContractSerializer. It looks something like this:

namespace Foo
{
    [DataContract(Name = "Bar")]
    class Bar
    {
        class A
        {
            public A(object a, object b, object c)
            {
                d = a;
                e = b;
                f = c;
            }
            public object d;
            public object e;
            public object f;
        }

        [DataMember]
        private ArrayList lst = new ArrayList();
        ...
    }
}

When I try to serialize this class, I get an error:

"System.Runtime.Serialization.SerializationException: Type 'Foo.Bar+A' with data contract name '...' is not expected. Consider using a DataContractResolver if you are using DataContractSerializer or add any types not known statically to the list of known types."

What I want to do is ignore A. It is just the definition of a type. None of the DataMembers I am trying to serialize are of type A.

Edit: This is the serialization code.

public void Serialize()
{
    var writer = new FileStream("testoutput.xml", FileMode.Create);
    var serializer = new DataContractSerializer(typeof(Bar));
    serializer.WriteObject(writer, this);
    writer.Close();
}

The exception is thrown on serializer.WriteObject.

Answer 1

After poking around a little bit more, I was able to fix it like this:

[KnownType(typeof(A))]
[DataContractAttribute]
class A
{
    public A(object a, object b, object c)
    {
        d = a;
        e = b;
        f = c;
    }
    [DataMember]
    public object d;
    [DataMember]
    public object e;
    [DataMember]
    public object f;
}

I think that one of the arraylists was actually holding As. This class is massive, so I probably just missed it.