Develop Reference

How to serialize & deserialize static reference object?

i want to serialize & deserialize a object (this object has reference) using BinaryFormatter.
i have expected that 'DeserializedObject.Equals(A.Empty)' is same to below code.
but, a result is different.
in order to 'DeserializedObject == A.Empty', how to use serialize/deserialize ?
[Serializable]
public class A
{
private string ID = null;
private string Name = null;
public A()
{ }
public static A Empty = new A()
{
ID = "Empty",
Name = "Empty"
};
}
class Program
{
static void Main(string[] args)
{
A refObject = A.Empty; // Add reference with static object(Empty)
A DeserializedObject;
//Test
//before serialization, refObject and A.Empty is Same!!
if(refObject.Equals(A.Empty))
{
Console.WriteLine("refObject and A.Empty is the same ");
}
//serialization
using (Stream stream = File.Create("C:\\Users\\admin\\Desktop\\test.mbf"))
{
BinaryFormatter bin = new BinaryFormatter();
bin.Serialize(stream, refObject);
}
//Deserialization
using (Stream stream = File.Open("C:\\Users\\admin\\Desktop\\test.mbf", FileMode.Open))
{
BinaryFormatter bin = new BinaryFormatter();
DeserializedObject = (A)bin.Deserialize(stream);
}
//compare DeserializedObject and A.Empty again.
//After deserialization, DeserializedObject and A.Empty is Different!!
if (DeserializedObject.Equals(A.Empty))
{
Console.WriteLine("Same");
}
else
Console.WriteLine("Different");
}
}

The reason for this is that they are different objects! You can check this by printing their GetHashCode(). The reason for this is that in your code:
refObject is a reference to A.Empty (and thus the same object)
DeserialisedObject is NOT a copy; it is a new instance and so a
different object
However DeserializedObject should contain the same values (ID and Name). Note that refObject.ID will be the same object as A.Empty.ID; DeserialisedObject.ID will not, although is should contain (a copy of) the same data.
If you're just testing that deserialization is working, test that the values contained by DeserializedObject and A.Empty are the same.

If you have an immutable type which has one or more global singletons that represent standard values of the type (A.Empty in your case), you can implement the IObjectReference interface and make BinaryFormatter replace deserialized instances of the type with the appropriate, equivalent global singleton. Thus:
[Serializable]
public class A : IObjectReference
{
private string ID = null;
private string Name = null;
public A()
{ }
public static A Empty = new A()
{
ID = "Empty",
Name = "Empty"
};
#region IObjectReference Members
object IObjectReference.GetRealObject(StreamingContext context)
{
if (this.GetType() == Empty.GetType() // Type check because A is not sealed
&& this.ID == Empty.ID
&& this.Name == Empty.Name)
return Empty;
return this;
}
#endregion
}
And, to test:
public class TestClass
{
public static void Test()
{
A refObject = A.Empty; // Add reference with static object(Empty)
Test(refObject, true);
A dummy = new A(); // No global singleton for this one.
Test(dummy, false);
}
private static void Test(A refObject, bool shouldBeEqual)
{
Console.WriteLine(string.Format("refObject and A.Empty are {0}.", object.ReferenceEquals(refObject, A.Empty) ? "identical" : "different"));
var binary = BinaryFormatterHelper.ToBase64String(refObject);
var DeserializedObject = BinaryFormatterHelper.FromBase64String<A>(binary);
Console.WriteLine(string.Format("DeserializedObject and A.Empty are {0}.", object.ReferenceEquals(DeserializedObject, A.Empty) ? "identical" : "different"));
Debug.Assert(object.ReferenceEquals(refObject, A.Empty) == object.ReferenceEquals(DeserializedObject, A.Empty)); // No assert
Debug.Assert(shouldBeEqual == object.ReferenceEquals(refObject, DeserializedObject)); // No assert
}
}
public static class BinaryFormatterHelper
{
public static string ToBase64String<T>(T obj)
{
using (var stream = new MemoryStream())
{
new BinaryFormatter().Serialize(stream, obj);
return Convert.ToBase64String(stream.GetBuffer(), 0, checked((int)stream.Length)); // Throw an exception on overflow.
}
}
public static T FromBase64String<T>(string data)
{
return FromBase64String<T>(data, null);
}
public static T FromBase64String<T>(string data, BinaryFormatter formatter)
{
using (var stream = new MemoryStream(Convert.FromBase64String(data)))
{
formatter = (formatter ?? new BinaryFormatter());
var obj = formatter.Deserialize(stream);
if (obj is T)
return (T)obj;
return default(T);
}
}
}

serialization on a wrapper class with a dictionary of nested class?

I have two classes that need to be serialized to a file. Here is the basic Item class.
[Serializable()]
public class Item:ISerializable,...
{
......
private string _itemName;
[NonSerialized]
private Inventory _myInventory;
private double _weight;
....
event PropertyChangingEventHandler propertyChanging;
event PropertyChangingEventHandler INotifyPropertyChanging.PropertyChanging
{
add { propertyChanging += value;}
remove { propertyChanging -= value; }
}
public string Name {get;set;....}
public double Weight {get;set;...}
....
public void GetObjectData(SerializationInfo info, StreamingContext context)
{
info.AddValue("Name", _itemName);
info.AddValue("Weight", _weight);
Type t = this.GetType();
info.AddValue("TypeObj", t);
}
internal Item(SerializationInfo info, StreamingContext context)
{
_itemName = info.GetString("Name");
_weight = info.GetDouble("Weight");
}
And here is the Inventory class:
[Serializable()]
public class Inventory:......
{
private int _numOfProduct = 0;
private int _numOfItems = 0;
private Dictionary<string, Item> _inventoryDictionary = new Dictionary<string, Item>();
.....
public IEnumerable<Item> GetSortedProductsByName()
{
return _inventoryDictionary.OrderBy(key => key.Key).Select(key => key.Value).ToList();
}
.....
}
When I tested the binary serialization to files with:
//serialize
....
fs = File.OpenWrite(FileName); //FileName = "C:/temp/foo.bin"
b.Serialize(fs, products);
fs.Close();
....
//deserialize
Inventory products = new Inventory();
BinaryFormatter b = new BinaryFormatter();
fs = File.OpenRead(FileName);
products = (Inventory)b.Deserialize(fs);
...
When I tested the serialization it appears that the following code doesn't work as expected:
....
foreach (var item in products.GetSortedProductsByName())
{
Console.WriteLine(item.Name);
}
....
I debugged through the lines and found that item is always null although product is not null.
Any thoughts?
If anyone knows somewhere that I can find a similar sample implementation of my scenario, please let me know.

How to maintain object reference when serializing

Okay, I'm a little fuzzy on how this works or if it's possible. I want to serialize the Child class, but I don't actually want to serialize a Parent object when it does the Child.MyParent field... I just want the reference to be serialized. Is this possible and how would I go about it?
public class Parent
{
public Child New()
{
return new Child(this);
}
}
public class Child
{
public Parent MyParent;
public Child(Parent parent)
{
MyParent = parent;
}
}
Edit: I'm using DataContractSerializer, but I'm not opposed to switching to something else if necessary.

The XMLIgnoreAttribute can be applied to fields that you don's want serialized. For example,
public class Child
{
[XmlIgnore]
public Parent MyParent;
public Child(Parent parent)
{
MyParent = parent;
}
}
But as far as serializing a reference to the field, you'd have to provide more info on how you plan to persist the object that the reference points to. What is your reason to not just serialize the Parent member (in your case)? It's common to serialize all the public members that are needed.
If you just want to use serialization to clone, something like this should work:
private static Parent Clone(Parent parent)
{
Parent parentClone = null;
lock (m_lock) // serialize cloning.
{
IFormatter formatter = new BinaryFormatter();
MemoryStream stream = new MemoryStream();
using (stream)
{
formatter.Serialize(stream, parent);
stream.Seek(0, SeekOrigin.Begin);
parentClone = (Parent)formatter.Deserialize(stream);
}
}
return parentClone;
}

Sounds like you might need to implement your own serialization and deserialization functionality.
http://msdn.microsoft.com/en-us/library/system.runtime.serialization.iserializable.getobjectdata.aspx
Here's an extract from MSDN
[Serializable]
public class Person : ISerializable
{
private string name_value;
private int ID_value;
public Person() { }
protected Person(SerializationInfo info, StreamingContext context)
{
if (info == null)
throw new System.ArgumentNullException("info");
name_value = (string)info.GetValue("AltName", typeof(string));
ID_value = (int)info.GetValue("AltID", typeof(int));
}
[SecurityPermission(SecurityAction.LinkDemand,Flags = SecurityPermissionFlag.SerializationFormatter)]
public virtual void GetObjectData(SerializationInfo info, StreamingContext context)
{
if (info == null)
throw new System.ArgumentNullException("info");
info.AddValue("AltName", "XXX");
info.AddValue("AltID", 9999);
}
public string Name
{
get { return name_value; }
set { name_value = value; }
}
public int IdNumber
{
get { return ID_value; }
set { ID_value = value; }
}
}

.NET Serializable entity

I need to make all my entities serializable. So I was thinking in a BaseEntity with a Backup and a Restore method. But in the restore I can't override the object with the saved one because this is read-only.
Any solution or some other way to get the serializable entities?
My code:
internal class BaseEntity
{
private MemoryStream ms = new MemoryStream();
private BinaryFormatter bf = new BinaryFormatter();
public void Backup()
{
bf.Serialize(ms, this);
}
public void Restore()
{
this = (BaseEntity)bf.Deserialize(ms);
}
}

The more common pattern is to not make it the responsibility of your objects to serialize/deserialize themselves; rather, use an external serializer:
var serializer = new DataContractJsonSerializer(typeof(YourClass));
var stream = ...;
YourClass yourObj = ...;
serializer.WriteObject(stream, yourObj);
var restoredObj = serializer.ReadObject(stream);

Edit: One way serialization can work is to use the System.Runtime.Serialization.Formatters.Binary.BinaryFormatter (or other implementation of IFormatter). To serialize an object you pass the object and a stream. To Deserialize the object, you pass a stream (positioned at the begining of your serialized data), and it returns the serialized object and all its depenedencies.
public static class EntityBackupServices
{
public static MemoryStream Backup (BaseEntity entity)
{
var ms = new MemoryStream();
Serialize (ms, entity);
ms.Position = 0;
return ms;
}
public static void Serialize (Stream stream, BaseEntity entity)
{
var binaryFormatter = new BinaryFormatter();
binaryFormatter.Serialize (stream, entity);
}
public static BaseEntity Restore (Stream stream)
{
var binaryFormatter = new BinaryFormatter();
var entity = (BaseEntity) binaryFormatter.Deserialize (stream);
return entity;
}
}
One thing a formatter don't do (though the FormatterServices class makes it possible) is modify existing objects. So you probably don't want to have an instance method called Deserialize. You can't really do this: new LionEntity().Deserialize () where it replaces the fields of an existing instance.
Note: You'll need to put Serializable over all your types. Any fields that can't be serialized (because it's either not a struct, or it's not marked as [Serializable] will need to be marked with NonSerialized.
// A test object that needs to be serialized.
[Serializable()]
public class BaseEntity
{
public int member1;
public string member2;
public string member3;
public double member4;
// A field that is not serialized.
[NonSerialized()] public MyRuntimeType memberThatIsNotSerializable;
public TestSimpleObject()
{
member1 = 11;
member2 = "hello";
member3 = "hello";
member4 = 3.14159265;
memberThatIsNotSerializable = new Form ();
}
public MemoryStream Backup ()
{
return EntityBackupServices.Backup (this);
}
}
Edit:
The way I've mentioned is a rather standard and accepted way. If you want to venture into hackdom, you can deserialize the object the way I've mentioned, then use reflection to set each field on your existing object to the value of the deserialized object.
public class BaseEntity
{
void Restore(Stream stream)
{
object deserialized = EntityBackupServices.RestoreDeserialize(stream);//As listed above
if (deserialized.GetType () != this.GetType ())
throw new Exception();
foreach (FieldInfo fi in GetType().GetFields())
{
fi.SetValue(this, fi.GetValue (deserialized));
}
}
}

public IEntidadBase Restore()
{
return (IEntidadBase)bf.Deserialize(ms);
}
#jacklondon how would you do EntitySerializer methods?
You can do serialization process with http://www.servicestack.net/ StackService.Text module for clean entities. You don't need any attribute (serializable/datacontract) in ms way.
public class EntityFoo
{
public string Bar { get; set; }
public EntityFoo (string bar)
{
Bar = bar;
}
}
public class EntityDumper //and the EntitySerializer
{
public static string Dump<T> (T entity)
{
return new TypeSerializer<T> ().SerializeToString (entity);
}
public static T LoadBack<T> (string dump)
{
return new TypeSerializer<T> ().DeserializeFromString (dump);
}
}
public class dump_usage
{
public void start ()
{
string dump = EntityDumper.Dump (new EntityFoo ("Space"));
EntityFoo loaded = EntityDumper.LoadBack<EntityFoo> (dump);
Debug.Assert (loaded.Bar == "Space");
}
}

I don't necessarily recommend this, but here is one pattern for an object that can persist and restore its own state using serialization that creates new instances:
public sealed class MyClass
{
private Data _data = new Data();
//Properties go here (access the public fields on _data)
public void Backup()
{
//Serialize Data
}
public void Restore()
{
//Deserialize Data and set new instance
}
private sealed class Data
{
//Public fields go here (they're private externally [because Data is private], but public to MyClass.)
}
}
Note that this only works if your serializer supports non-public classes. Worst-case, you have to make the nested class public, which is ugly, but doesn't hurt encapsulation (since the instance is private).

Copy two identical object with different namespaces (recursive reflection)

I'm working in c# with several workspaces that have one specific class which his always the same in each workspace.
I would like to be able have a copy of this class to be able to work with it without dealing with namespaces differences.
example :
namespace1 {
class class1{
public class2;
}
class class2{
public string;
}
}
namespace2 {
class class1{
public class2;
}
class class2{
public string;
}
}
In my copied Class I've got a function to copy all data's to one of the namespace's class.
It's working if i only have c# standard types. I got exeption ( "Object does not match target type." ) as soon as I'm dealing with class2 object (which is also from different namespaces)
public Object toNamespaceClass(Object namespaceClass)
{
try
{
Type fromType = this.GetType();
Type toType = namespaceClass.GetType();
PropertyInfo[] fromProps = fromType.GetProperties();
PropertyInfo[] toProps = toType.GetProperties();
for (int i = 0; i < fromProps.Length; i++)
{
PropertyInfo fromProp = fromProps[i];
PropertyInfo toProp = toType.GetProperty(fromProp.Name);
if (toProp != null)
{
toProp.SetValue(this, fromProp.GetValue(namespaceClass, null), null);
}
}
}
catch (Exception ex)
{
}
return namespaceClass;
}
Anyone do have any idea of how to deal with this kind of "recursivity reflection".
I hope eveything is understandable.
Thanks, Bye!
Edit :
I think i got it solved (at least in my mind), I'll try the solution back at work tomorrow. Taking my function out of my class and using it recursively if a property is not a standard type is maybe the solution.

BinaryFormatter does not work in .Net 4.5 as it remembers from what type of class the instance was created. But with JSON format, it does not. JSON serializer is implemented by Microsoft in DataContractJosnSerializer.
This works:
public static T2 DeepClone<T1, T2>(T1 obj)
{
DataContractJsonSerializer serializer = new DataContractJsonSerializer(typeof(T1));
DataContractJsonSerializer deserializer = new DataContractJsonSerializer(typeof(T2));
using (var ms = new MemoryStream())
{
serializer.WriteObject(ms, obj);
ms.Position = 0;
return (T2)deserializer.ReadObject(ms);
}
}
and uses as follows:
var b = DeepClone<A, B>(a);

I had the similar problem. I got to use similar classes but different in terms of namespace only. As a quick solution I performed below steps and it works.
Serialize source class into XML.
In SerializedXML replace source namespace with the target one.
DeSerialize with target type.
I know there is performance overhead with above way but it is quick to implement and error free.

I got it solved , just to let you know how I did it :
This solution is sot perfect because it handle only 1 dimensions array not more.
public static Object CopyObject(Object from , Object to)
{
try
{
Type fromType = from.GetType();
Type toType = to.GetType();
PropertyInfo[] fromProps = fromType.GetProperties();
PropertyInfo[] toProps = toType.GetProperties();
for (int i = 0; i < fromProps.Length; i++)
{
PropertyInfo fromProp = fromProps[i];
PropertyInfo toProp = toType.GetProperty(fromProp.Name);
if (toProp != null)
{
if (toProp.PropertyType.Module.ScopeName != "CommonLanguageRuntimeLibrary")
{
if (!toProp.PropertyType.IsArray)
{
ConstructorInfo ci = toProp.PropertyType.GetConstructor(new Type[0]);
if (ci != null)
{
toProp.SetValue(to, ci.Invoke(null), null);
toProp.SetValue(to, gestionRefelexion.CopyObject(fromProp.GetValue(from, null), toProp.GetValue(to, null)), null);
}
}
else
{
Type typeToArray = toProp.PropertyType.GetElementType();
Array fromArray = fromProp.GetValue(from, null) as Array;
toProp.SetValue(to, copyArray(fromArray, typeToArray), null);
}
}
else
{
toProp.SetValue(to, fromProp.GetValue(from, null), null);
}
}
}
}
catch (Exception ex)
{
}
return to;
}
public static Array copyArray(Array from, Type toType)
{
Array toArray =null;
if (from != null)
{
toArray= Array.CreateInstance(toType, from.Length);
for (int i = 0; i < from.Length; i++)
{
ConstructorInfo ci = toType.GetConstructor(new Type[0]);
if (ci != null)
{
toArray.SetValue(ci.Invoke(null), i);
toArray.SetValue(gestionRefelexion.CopyObject(from.GetValue(i), toArray.GetValue(i)), i);
}
}
}
return toArray;
}
Hope this can help some people.
Thanks for helping everyone.
Cheers

public static T DeepClone<T>(T obj)
{
using (var ms = new MemoryStream())
{
var formatter = new BinaryFormatter();
formatter.Serialize(ms, obj);
ms.Position = 0;
return (T) formatter.Deserialize(ms);
}
}
from here

Two identical or similar objects from different namespaces ?
You have this:
namespace Cars
{
public class car {
public string Name;
public void Start() { ... }
}
}
namespace Planes
{
public class plane {
public string Name;
public void Fly() { ... }
}
}
Time to apply some class inheritance:
namespace Vehicles
{
public class vehicle
{
public string Name;
} // class
} // namespace
using Vehicles;
namespace Cars
{
public class car: vehicle
{
public string Name;
public void Start() { ... }
} // class
} // namespace
using Vehicles;
namespace Planes
{
public class plane: vehicle
{
public void Fly() { ... }
}
}
And to copy, there is a copy method or constructor, but, I prefer a custom one:
namespace Vehicles
{
public class vehicle {
public string Name;
public virtual CopyFrom (vehicle Source)
{
this.Name = Source.Name;
// other fields
}
} // class
} // namespace
Cheers.

You either need to refactor all of your duplicate classes into a single shared class or implement a common interface that all of your various classes implement. If you really can't modify the underlying types, create a subclass for each that implements your common interface.
Yes, you can do it with reflection... but you really shouldn't because you end up with brittle, error prone, code.

This problem can be elegantly solves using Protocol Buffers because Protocol Buffers do not hold any metadata about the type they serialize. Two classes with identical fields & properties serialize to the exact same bits.
Here's a little function that will change from O the original type to C the copy type
static public C DeepCopyChangingNamespace<O,C>(O original)
{
using (MemoryStream ms = new MemoryStream())
{
Serializer.Serialize(ms, original);
ms.Position = 0;
C c = Serializer.Deserialize<C>(ms);
return c;
}
}
usage would be
namespace1.class1 orig = new namespace1.class1();
namespace2.class1 copy =
DeepCopyChangingNamespace<namespace1.class1, namespace2.class1>(orig);