Clone an Object Using Serialization

Category:

C#, VB.NET, ASP.NET

Type:

Snippets

Difficulty:

Intermediate

Author:

Intelligent Solutions Inc.

Version Compatibility: Visual Basic.NET, ASP.NET

More information:

This snippet allows you to create a copy (clone) of an object by serializing the original into a memory stream and then deserilaizing it out. It also contains a demo which illustrates how to use the code and the difference between cloning an object using this method as opposed to creating a new reference to it using the = operator.

Note that the object copied must be marked as serializiable. If the class definition for the object contains a member that is not marked as serializable, the method will fail (refer to the comments in declarations for more info).

Instructions: Copy the declarations and code below and paste directly into your VB project.

Declarations:
Imports System.Runtime.Serialization.Formatters.Binary Imports System.Runtime.Serialization Imports System.IO 'CLASS OBJECT FOR DEMOS <Serializable()> Public Class clsItem Private m_strName As String Private m_strValue As String Private m_strNewValue As String Private m_blnRequired As Boolean Private m_blnIsDate As Boolean Private m_blnIsNumber As Boolean 'Public oCollection as collection 'If above is uncommented, cloning fails Public Property Name() As String Get Return m_strName End Get Set(ByVal Value As String) m_strName = Value End Set End Property Public Property Value() As String Get Return m_strValue End Get Set(ByVal Value As String) m_strValue = Value End Set End Property Public Property NewValue() As String Get Return m_strNewValue End Get Set(ByVal Value As String) m_strNewValue = NewValue End Set End Property Public Property IsDate() As Boolean Get Return m_blnIsDate End Get Set(ByVal Value As Boolean) m_blnIsDate = Value End Set End Property Public Property IsNumber() As Boolean Get Return m_blnIsNumber End Get Set(ByVal Value As Boolean) m_blnIsNumber = Value End Set End Property Public Property Required() As Boolean Get Return m_blnRequired End Get Set(ByVal Value As Boolean) m_blnRequired = Value End Set End Property Public ReadOnly Property CurrentValue() As String Get Return IIf(NewValue = "", Value, NewValue) End Get End Property Public Function Dirty() As Boolean Return NewValue <> Value End Function End Class

Code:

Function ObjectCopy(ByVal obj As Object) As Object
        'copies original object to stream then 
        'deserializes that stream and returns the output
        'to create clone (copy) of object

Dim objMemStream As New MemoryStream(5000)
        Dim objBinaryFormatter As New BinaryFormatter(Nothing, _
            New StreamingContext(StreamingContextStates.Clone))

objBinaryFormatter.Serialize(objMemStream, obj)

objMemStream.Seek(0, SeekOrigin.Begin)

ObjectCopy = objBinaryFormatter.Deserialize(objMemStream)

objMemStream.Close()
    End Function

'DEMO
Dim objName1 As New clsItem()
                    Dim objname2 As clsItem

With objName1
                        .Name = "TestNumericValue"
                        .Value = "4"
                        .IsNumber = True
                    End With
                    objname2 = ObjectCopy(objName1)

System.Diagnostics.Debug.WriteLine(objname2.Name)
System.Diagnostics.Debug.WriteLine(objname2.Value)
System.Diagnostics.Debug.WriteLine(objname2.IsNumber)
System.Diagnostics.Debug.WriteLine(objname2 Is objName1) 
'false, it's a clone.

objname2.Name = "Number4"
System.Diagnostics.Debug.WriteLine(objName1.Name)
'can make changes to objname2 without affecting objname1

Dim objName3 As clsItem = objName1
System.Diagnostics.Debug.WriteLine(objname3 Is objName1) 
'true, it's the same instance

objName3.Name = "Number4"
System.Diagnostics.Debug.WriteLine(objName1.Name)
'anything you do to obj3 is reflected in obj1