Not able to deserialize Lazy object
I want to Serialize and DeSerialize an object which contains a Lazy Collection of some custom objects.
Normally everything works perfectly fine but, if namespaces of classes used for serialization are changed, then this issue occurs.
I have written a SerializationBinder to point to right classes while deserializing. But for some reason, I am not getting deserialized values.
Following code snippet explains the problem that I am getting;
Classes used for Serialization:
namespace ConsoleApplication14
{
[Serializable]
public class MyInnerClass : ISerializable
{
private string _stringInInnerClassKey = "StringInInnerClass";
public string StringInInnerClass { get; set; }
public MyInnerClass() { }
private MyInnerClass(SerializationInfo info, StreamingContext context)
{
StringInInnerClass = info.GetString(_stringInInnerClassKey);
}
public void GetObjectData(SerializationInfo info, StreamingContext context)
{
info.AddValue(_stringInInnerClassKey, StringInInnerClass);
}
}
[Serializable]
public class MyOuterClass : ISerializable
{
private string _collectionOfObjKey = "CollectionOfInnerObj";
public Lazy<Collection<MyInnerClass>> CollectionOfInnerObj { get; set; }
private MyOuterClass(SerializationInfo info, StreamingContext context)
{
if (info == null) throw new ArgumentNullException("serializationInfo");
CollectionOfInnerObj =
(Lazy<Collection<MyInnerClass>>)
info.GetValue(_collectionOfObjKey, typeof(Lazy<Collection<MyInnerClass>>));
}
public MyOuterClass() { }
public void GetObjectData(SerializationInfo info, StreamingContext context)
{
if (info == null) throw new ArgumentNullException();
info.AddValue(_collectionOfObjKey, CollectionOfInnerObj, typeof(Lazy<Collection<MyInnerClass>>));
}
}
}
Above same classes are used for Deserialization but only namespace is changed to ConsoleApplication14.OtherNamespace
For such Deserialization to work, I have used following SerializationBinder class:
public class MyBinder : SerializationBinder
{
public override Type BindToType(string assemblyName, string typeName)
{
if (assemblyName.Equals(
"ConsoleApplication14, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null"))
{
if (typeName.Equals("ConsoleApplication14.MyOuterClass"))
return typeof(ConsoleApplication14.OtherNamespace.MyOuterClass);
if (typeName.Equals("ConsoleApplication14.MyInnerClass"))
return typeof(ConsoleApplication14.OtherNamespace.MyInnerClass);
}
if (assemblyName.Equals("mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"))
{
if (typeName.Equals(
"System.Collections.ObjectModel.Collection`1[[ConsoleApplication14.MyInnerClass, ConsoleApplication14, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]]"))
return typeof(Collection<ConsoleApplication14.OtherNamespace.MyInnerClass>);
if (typeName.Equals(
"System.Collections.Generic.List`1[[ConsoleApplication14.MyInnerClass, ConsoleApplication14, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]]"))
return typeof(List<ConsoleApplication14.OtherNamespace.MyInnerClass>);
if (typeName.Equals(
"System.Lazy`1[[System.Collections.ObjectModel.Collection`1[[ConsoleApplication14.MyInnerClass, ConsoleApplication14, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]], mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]]"))
return typeof(Lazy<Collection<ConsoleApplication14.OtherNamespace.MyInnerClass>>);
//I THINK, MAYBE THIS 'IF' CONDITION IS THE PROBLEM, BUT DONT KNOW HOW TO FIX THIS.
if (typeName.Equals(
"System.Lazy`1+Boxed[[System.Collections.ObjectModel.Collection`1[[ConsoleApplication14.MyInnerClass, ConsoleApplication14, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]], mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]]"))
return typeof(Lazy<Collection<ConsoleApplication14.OtherNamespace.MyInnerClass>>);
}
return Type.GetType(String.Format("{0}, {1}", typeName, assemblyName));
}
}
Serialization and Deserialization of object of MyCustomClass :
public static void Main(string[] args)
{
//----------------Object Creation----------------------
var objToSerialize = new MyOuterClass
{
CollectionOfInnerObj =
new Lazy<Collection<MyInnerClass>>(
() => new Collection<MyInnerClass>
{
new MyInnerClass
{
StringInInnerClass = "a"
},
new MyInnerClass
{
StringInInnerClass = "aa"
},
})
};
//------------------------------------------------------
//---------------------Serialization---------------------
using (var stream = File.Create("E:tempFile.tmp"))
{
var binaryFormatter = new BinaryFormatter();
binaryFormatter.Serialize(stream, objToSerialize);
stream.Close();
}
//------------------------------------------------------
//-------------------DeSerialization--------------------
using (var stream = File.OpenRead("E:tempFile.tmp"))
{
var binaryFormatter = new BinaryFormatter {Binder = new MyBinder()};
var objOfOtherNamespaceClass = (OtherNamespace.MyOuterClass) binaryFormatter.Deserialize(stream);
//Getting NullReferenceException when Value property of objOfOtherNamespaceClass.CollectionOfInnerObj is called
foreach (OtherNamespace.MyInnerClass stringVal in objOfOtherNamespaceClass.CollectionOfInnerObj.Value)
Console.WriteLine(stringVal.StringInInnerClass);
stream.Close();
}
//-----------------------------------------------------
}
I am getting NullReferenceException when Value property of deserialized Lazy object is called. (ie when objOfOtherNamespaceClass.CollectionOfInnerObj.Value is called)
Please help me resolve this issue...
Problem is in line already highlighted by you
//I THINK, MAYBE THIS 'IF' CONDITION IS THE PROBLEM, BUT DONT KNOW HOW TO FIX THIS.
if (typeName.Equals(
"System.Lazy`1+Boxed[[System.Collections.ObjectModel.Collection`1[[ConsoleApplication14.MyInnerClass, ConsoleApplication14, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]], mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]]"))
return typeof(Lazy<Collection<ConsoleApplication14.OtherNamespace.MyInnerClass>>);
Please change this code to following
if (typeName.Equals(
"System.Lazy`1+Boxed[[System.Collections.ObjectModel.Collection`1[[ConsoleApplication14.MyInnerClass, ConsoleApplication14, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]], mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]]"))
{
return Type.GetType(typeName.Replace("ConsoleApplication14.MyInnerClass", "ConsoleApplication14.OtherNamespace.MyInnerClass"));
}
Type should be Boxed class, declared inside Lazy source code
public class Lazy<T>
{
#region Inner classes
/// <summary>
/// wrapper class to box the initialized value, this is mainly created to avoid boxing/unboxing the value each time the value is called in case T is
/// a value type
/// </summary>
[Serializable]
class Boxed
{
internal Boxed(T value)
{
m_value = value;
}
internal T m_value;
}
Hope this help.
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