Serialization Circular exception caused by self-referencing Read-only property

When trying to return an object from a JSON asp.net 3.5SP1 WebService (not WCF, classic asp.net WebService with scriptservice attribute), I have an "A circular reference was detected while serializing an object of type 'Geo.Bound'" err开发者_StackOverflowor, caused by a self-referencing Read-only property :

Simplified Code :

Namespace Geo
<DataContract(Namespace:="Geo", IsReference:=True)> _
Public Class Bound

 <DataMember(Name:="sw", IsRequired:=False)> _
 Public SouthWestCoord As Double


 Public Sub New()
  SouthWestCoord = 1.5#
 End Sub

 <IgnoreDataMember()> _
 Public ReadOnly Property Bds() As Bound
  Get
   Return Me
  End Get
 End Property

End Class
End Namespace

• I want to keep the Read-Only property because it's used for implementing an interface.
• Adding a "IsReference:=True" attribute to Bound class changes nothing.
• If I use a DataContractJsonSerializer (outside the context of webservice, like this exemple : link text), it works and I have a correct JSON.
• If I remove the "Bds" Read-only property it works !!

I don't understand why ! It's a readonly property, without a DataMember attribute, with a IgnoreDatamember attribute, it's not supposed to be serialized !

How to keep the "Bds" property, and get rid of the circular reference exception ?

Thanks !

Here is example, that works (sorry for C#)

1. Defined class:

   [DataContract(Namespace = "Geo")]
   public class Bound
   {
       [IgnoreDataMember]
       public Bound { get { return this; } }
   
   
      [DataMember]
      public string Name { get; set; }
   }
   

2. Created Service Interface (and implementation)

   [ServiceContract]
   public interface IService1
   {
       [OperationContract]
       [WebInvoke(Method = "GET", ResponseFormat = WebMessageFormat.Json)]
       Bound DoWork();
   }
   
   
   public class Service1 : IService1
   {
       public Bound DoWork()
       {
           return new Bound { Name = "Test Name" };
       }
   }
   

3. Edited system.serviceModel part of app.config

   <behaviors>
     <endpointBehaviors>
       <behavior name="endBeh">
         <enableWebScript/>
       </behavior>
     </endpointBehaviors>
   </behaviors>
   <services>
     <service name="JsonSerializationTest.Service1">
       <endpoint address="" binding="webHttpBinding" behaviorConfiguration="endBeh" contract="JsonSerializationTest.IService1" />
       <host>
         <baseAddresses>
           <add baseAddress="http://localhost:8732/Design_Time_Addresses/JsonSerializationTest/Service1/"/>
         </baseAddresses>
       </host>
     </service>
   </services>
   

4. Started Service Host in Program.cs

   using (var sh = new ServiceHost(typeof(Service1)))
   {
       sh.Open();
       Console.WriteLine("Opened");
       Console.ReadLine();
   }
   

Started program, opened browser, typed http://localhost:8732/Design_Time_Addresses/JsonSerializationTest/Service1/DoWork and recieved Json-ed test object:

{"d":{"__type":"Bound:Geo","Name":"Test Name"}}

PS: WebInvokeAttribute is located in System.ServiceModel.Web.dll assembly.

You are getting the circular reference Because it's the class Bound with a reference to a property of type Bound. That means it's an endless supply of Bound objects.

Not sure on why IgnoreDataMember isn't working right. I will give this some more time and update my answer if I have any ideas.