Originally posted on: http://geekswithblogs.net/mnf/archive/2013/06/02/serialization-error-when-property-is-declared-as-base-class-but.aspx
I've receive quite generic error Message :
Type 'MyclassType' with data contract name 'MyclassType:http://schemas.datacontract.org/myNamespace' is not expected. Consider using a DataContractResolver or 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.
Type : System.Runtime.Serialization.SerializationException, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089
After investigation I found that the class that I tried to serialize, had a property declared of the base class, but at runtime derived class was assigned, and serialization was unable to resolve it.
The fix was simple- to add KnownType property to container class.
[KnownType(typeof(MyclassType))]
public class Mycontainer
{
MyBaseclass PropertyOfmyClass { get; set;}
.......
}
public class MyclassType : MyBaseclass
{ ....}
Unfortunately, the serialization time error message didn't specify the name of container class , not the name of property. it makes harder to fix the error.