Exception during the serialization - Type with data contract name is not expected

Question

I have this classes:

[DataContract]
class ClassA
{
    [DataMember]
    public Object Value; // and this can be of ClassB or some primitive type.
    ...
}

[DataContract]
class ClassB : IEnumerable<KeyValuePair<String, ClassA>>
{
    [DataMember]
    private Dictionary<String, ClassA> dictionary;
    ...
}

but getting this exception when serialization take place:

Type 'MyNamespace.ClassA' with data contract name 'ClassA:http://schemas.datacontract.org/2004/07/MyNamespace' is not expected. Add any types not known statically to the list of known types - for example, by using the KnownTypeAttribute attribute or by adding them to the list of known types passed to DataContractSerializer.

I feel that I should use KnownType attribute, but I can't figure out how, because I am not owning IEnumerable<T>.

Can anyone help? Thanks.

Answer 1

Try the following:

[DataContract]
[KnownType(typeof(int))]
// Same way add here all the types that you are using in your class A.
class ClassA
{
    [DataMember]
    public int Value;
    ...
}