> Hi,
>
> I have a serializable class that has a NameValueCollection as a member
> object. As part of the deserialization process, via a callback during
> deserialization, the class needs to call various methods on the
> NameValueCollection. This is currently failing due to the internal
> state of NameValueCollection not being available, despite having a
> reference to the object.
>
> I have tried default serialization and implementing custom
> serialization via ISerializable. I have also tried implementing the
> callback using IDeserializationCallback and via the OnDeserialized
> attribute in .NET 2.0.
>
> I have simplified the test case down to the following, and I'd be
> grateful for any comments as to why it does not work. Note that if I
> comment out PrintCount() in the OnDeserialization method, the call in
> Main() does succeed.
>
> ---------------------8<---------------------
>
> using System;
> using System.Collections;
> using System.Collections.Specialized;
> using System.IO;
> using System.Runtime.Serialization;
> using System.Runtime.Serialization.Formatters.Binary;
>
> namespace Testcase
> {
>   class Program
>   {
>     static void Main(string[] args)
>     {
>       try
>       {
>         NVCWrapper nvcWrapper = new NVCWrapper();
>
>         // Serialize
>         MemoryStream memoryStream = new MemoryStream();
>         BinaryFormatter formatter = new BinaryFormatter();
>         formatter.Serialize(memoryStream, nvcWrapper);
>
>         // Deserialize
>         memoryStream.Seek(0, SeekOrigin.Begin);
>         NVCWrapper dsNvcWrapper = (NVCWrapper)
> formatter.Deserialize(memoryStream);
>
>         // Print count
>         dsNvcWrapper.PrintCount();
>       }
>       catch (Exception ex)
>       {
>         Console.Write("Exception:");
>         while (ex != null)
>         {
>           Console.WriteLine(Environment.NewLine);
>           Console.WriteLine(ex.GetType().ToString());
>           Console.WriteLine(ex.Message);
>           Console.WriteLine(ex.StackTrace);
>           ex = ex.InnerException;
>         }
>       }
>       finally
>       {
>         Console.WriteLine("Press a key to exit...");
>         Console.Read();
>       }
>     }
>   }
>
>   [Serializable]
>   public sealed class NVCWrapper : IDeserializationCallback
>   {
>     private NameValueCollection mNVC = new NameValueCollection();
>
>     public NVCWrapper()
>     {
>       mNVC.Add("TestName", "TestValue");
>     }
>
>     public void PrintCount()
>     {
>       Console.WriteLine("Count = " + mNVC.Count.ToString());
>     }
>
>     #region IDeserializationCallback Members
>
>     public void OnDeserialization(object sender)
>     {
>       PrintCount(); // NullReferenceException thrown from
> NameValueCollection's Count property.
>     }
>
>     #endregion
>   }
> }
>
> ---------------------8<---------------------
>
>
> Now, if I swap the implementation of NameValueCollection for the
> following stub class (updating the inline instantiation of
> NameValueCollection to MyNameValueCollection in NVCWrapper to point to
> the new class), the deserialization of NVCWrapper succeeds and no
> exception is thrown in OnDeserialization:
>
>
> ---------------------8<---------------------
>
>   [Serializable]
>   public sealed class MyNameValueCollection
>   {
>     ArrayList mNames = new ArrayList();
>     ArrayList mValues = new ArrayList();
>
>     public MyNameValueCollection()
>     {
>     }
>
>     public void Add(string name, string val)
>     {
>       mNames.Add(name);
>       mValues.Add(val);
>     }
>
>     public int Count
>     {
>       get { return mNames.Count; }
>     }
>   }
>
> ---------------------8<---------------------
>
>
> I'm just trying to understand what is wrong with the original test
> case, and under what circumstances (if any) you can rely on member
> objects being fully instantiated themselves when in a deserialization
> callback.
>
>
>
> Regards,
>
> Matt

> Hi,
>
> I have a serializable class that has a NameValueCollection as a member
> object. As part of the deserialization process, via a callback during
> deserialization, the class needs to call various methods on the
> NameValueCollection. This is currently failing due to the internal
> state of NameValueCollection not being available, despite having a
> reference to the object.
>
> I have tried default serialization and implementing custom
> serialization via ISerializable. I have also tried implementing the
> callback using IDeserializationCallback and via the OnDeserialized
> attribute in .NET 2.0.
>
> I have simplified the test case down to the following, and I'd be
> grateful for any comments as to why it does not work. Note that if I
> comment out PrintCount() in the OnDeserialization method, the call in
> Main() does succeed.
>
> ---------------------8<---------------------
>
> using System;
> using System.Collections;
> using System.Collections.Specialized;
> using System.IO;
> using System.Runtime.Serialization;
> using System.Runtime.Serialization.Formatters.Binary;
>
> namespace Testcase
> {
>   class Program
>   {
>     static void Main(string[] args)
>     {
>       try
>       {
>         NVCWrapper nvcWrapper = new NVCWrapper();
>
>         // Serialize
>         MemoryStream memoryStream = new MemoryStream();
>         BinaryFormatter formatter = new BinaryFormatter();
>         formatter.Serialize(memoryStream, nvcWrapper);
>
>         // Deserialize
>         memoryStream.Seek(0, SeekOrigin.Begin);
>         NVCWrapper dsNvcWrapper = (NVCWrapper)
> formatter.Deserialize(memoryStream);
>
>         // Print count
>         dsNvcWrapper.PrintCount();
>       }
>       catch (Exception ex)
>       {
>         Console.Write("Exception:");
>         while (ex != null)
>         {
>           Console.WriteLine(Environment.NewLine);
>           Console.WriteLine(ex.GetType().ToString());
>           Console.WriteLine(ex.Message);
>           Console.WriteLine(ex.StackTrace);
>           ex = ex.InnerException;
>         }
>       }
>       finally
>       {
>         Console.WriteLine("Press a key to exit...");
>         Console.Read();
>       }
>     }
>   }
>
>   [Serializable]
>   public sealed class NVCWrapper : IDeserializationCallback
>   {
>     private NameValueCollection mNVC = new NameValueCollection();
>
>     public NVCWrapper()
>     {
>       mNVC.Add("TestName", "TestValue");
>     }
>
>     public void PrintCount()
>     {
>       Console.WriteLine("Count = " + mNVC.Count.ToString());
>     }
>
>     #region IDeserializationCallback Members
>
>     public void OnDeserialization(object sender)
>     {
>       PrintCount(); // NullReferenceException thrown from
> NameValueCollection's Count property.
>     }
>
>     #endregion
>   }
> }
>
> ---------------------8<---------------------
>
>
> Now, if I swap the implementation of NameValueCollection for the
> following stub class (updating the inline instantiation of
> NameValueCollection to MyNameValueCollection in NVCWrapper to point to
> the new class), the deserialization of NVCWrapper succeeds and no
> exception is thrown in OnDeserialization:
>
>
> ---------------------8<---------------------
>
>   [Serializable]
>   public sealed class MyNameValueCollection
>   {
>     ArrayList mNames = new ArrayList();
>     ArrayList mValues = new ArrayList();
>
>     public MyNameValueCollection()
>     {
>     }
>
>     public void Add(string name, string val)
>     {
>       mNames.Add(name);
>       mValues.Add(val);
>     }
>
>     public int Count
>     {
>       get { return mNames.Count; }
>     }
>   }
>
> ---------------------8<---------------------
>
>
> I'm just trying to understand what is wrong with the original test
> case, and under what circumstances (if any) you can rely on member
> objects being fully instantiated themselves when in a deserialization
> callback.
>
>
>
> Regards,
>
> Matt