WCF Client Exception: error while trying to deserialize parameter

c#, wcf

Solution

you need `[DataContract]` and `[DataMember]` on the `Person` class

[DataContract]
public class Person : IPerson
{
    [DataMember]
    public string Name { get; set; }
}

`KnownTypeAttribute` is supposed to enable you to designate acceptable derived class for a given `DataContract`. It specifies types that should be recognised by the `DataContractSerializer` when Serializing or Deserializing a given type.

`GetPeopleResponse` does not derive from `Person` or `PersonExtended`...

Also there is a lot of stuff in your code that doesn't make sense at all to me... Here is something that makes sense to me...

public interface IPerson {
    string Name { get; set; }
}

public interface IPersonExtended : IPerson {
    List<IPerson> Contacts { get; set; }
}

[DataContract]
public class Person : IPerson {
    [DataMember]
    public string Name { get; set; }
}

[DataContract]
public class PersonExtended : Person, IPersonExtended {
    [DataMember]
    public List<Person> Contacts { get; set; }

    public PersonExtended() {
        Contacts = new List<Person>();
    }
}

[ServiceContract]
public interface IMyService {
    [OperationContract]
    IList<PersonExtended> GetAllPeople();
}

public class MyService : IMyService
{
    private IList<PersonExtended> _people;

    public MyService() {
        _people = new IList<PersonExtended>();
    }

    public IList<PersonExtended> GetAllPeople() {
        return _people
    }
}

Problem

I am getting this error when I try to call a WCF Service: The formatter threw an exception while trying to deserialize the message: There was an error while trying to deserialize parameter http://tempuri.org/:ResultValue. The InnerException message was 'Error in line 1 position 1741. Element 'htp://schemas.microsoft.com/2003/10/Serialization/Arrays:anyType' contains data from a type that maps to the name 'htp://schemas.datacontract.org/2004/07/DataAccess:Person'. The deserializer has no knowledge of any type that maps to this name. Consider using a DataContractResolver or add the type corresponding to 'Person' to the list of known types - for example, by using the KnownTypeAttribute attribute or by adding it to the list of known types passed to DataContractSerializer.'. I have a Interfaces project with the following definitions: ``` public interface IPerson { string Name { get; set; } } public interface IPersonExtended : IPerson { // If I remove the List of IPerson property, it works fine List<IPerson> Contacts { get; set; } } ``` I have a DataAccess project that implements the interfaces: ``` public class Person : IPerson { public string Name { get; set; } } public class PersonExtended : IPersonExtended { public string Name { get; set; } private List<IPerson> mContacts = new List<IPerson>(); // If I remove the List of IPerson property, it works fine public List<IPerson> Contacts { get { return mContacts; } set { mContacts = value; } } } ``` My Service Contract looks like this: ``` [ServiceContract] [ServiceKnownType(typeof(Person))] [ServiceKnownType(typeof(PersonExtended))] public interface IMyService { [OperationContract] ServiceCallResult<GetPeopleResponse> GetPeople(GetPeopleRequest request); } ``` My Service looks like: ``` public class MyService : IMyService { public ServiceCallResult<GetPeopleResponse> GetPeople(GetPeopleRequest request) { GetPeopleResponse response = new GetPeopleResponse(); // Get Some people that have contacts response.People = GetPeopleFromSomewhere(); ServiceCallResult<GetPeopleResponse> result = new ServiceCallResponse<GetPeopleResponse> { ResultValue = response }; return result; } } ``` And my response object looks like: ``` [DataContract] [KnownType(typeof(PersonExtended))] [KnownType(typeof(Person))] [KnownType(List<Person>))] [KnownType(List<PersonExtended))] public class GetPeopleResponse { [DataMember] public List<PersonExtended> People { get; set; } } ``` The Response object is just wrapped in a `MessageContract` object that contains status information, etc. EDIT If I remove the Contact (List) property through the entire workflow, it works fine. I'm wondering if it is related to trying to use a property with a list to an interface instead of a concrete object, but I'm not sure how to get around that with my project structure without adding a circular reference.

Original source