Datacontract exception. Cannot be serialized

Question

I have the following WCF DataContract:

[DataContract] public class Occupant {     private string _Name;     private string _Email;     private string _Organization;     private string _Badge;      public Occupant(string name, string badge, string organization)     {         Name = name;         Badge = badge;         Organization = organization;     }      public Occupant(string name, string badge)     {         Value = name;         Key = badge;     }      [DataMember]     public string Key     {         get { return _Name; }         set { _Name = value; }     }      [DataMember]     public string Value     {         get { return _Badge; }         set { _Badge = value; }     }      [DataMember]     public string Name     {         get { return _Name; }         set { _Name = value; }     }      [DataMember]     public string Email     {         get { return _Email; }         set { _Email = value; }     }      [DataMember]     public string Organization     {         get { return _Organization; }         set { _Organization = value; }     }      [DataMember]     public string Badge     {         get { return _Badge; }         set { _Badge = value; }     } } 

When I try to access this service via web browser (it is hosted on IIS), I am getting this error:

System.Runtime.Serialization.InvalidDataContractException: Type 'MyNamespace.Occupant' cannot be serialized. Consider marking it with the DataContractAttribute attribute, and marking all of its members you want serialized with the DataMemberAttribute attribute. If the type is a collection, consider marking it with the CollectionDataContractAttribute.

One of my methods is returning a List of type Occupant. Would this be causing it?

Answer 1

Because you have provided one or more initializing constructors, you will also need to add a parameterless (default) constructor.

i.e. You need to add:

[DataContract] public class Occupant {     // *** Needed only for Serialization     public Occupant() {}     ... 

This is because the default constructor disappears when you add an explicit constructor.

[The issue isn't with the method returning List<Occupant>, since methods aren't serialized).]

Answer 2

Try adding an empty constructor. Often times that will set off the serializer.