Serialize VB.NET objects without the events

'******************************************************************************
'*  File  NAME  :   SerilaizableObject.vb
'*
'*  AUTHOR      :   Trevor Hunter (hunter_trev@hotmail.com)
'*
'*  DATE        :   07/01/2004
'*
'*  DESCRIPTION :   An object used to help serialize VB objects without their events
'*
'******************************************************************************
Imports System.Runtime.Serialization
Imports System.Collections
Imports System.Reflection


'************************************************************************************************************
'*  NAME        :   SerializableObject
'*
'*  DESCRIPTION :   Implements a base class for a serializable object that removes event handlers
'*                  from the serialization process
'************************************************************************************************************
<Serializable()> _
Public MustInherit Class SerializableObject
    Implements ISerializable, IDeserializationCallback



    '*******************************************************************************
    ' New:  Default constructor
    ' 1) Blank Object
    ' 2) Deserialization Constructor
    '*******************************************************************************
    Public Sub New()
        MyBase.New()
    End Sub
    Protected Sub New(ByVal info As SerializationInfo, ByVal context As StreamingContext)

        ' Instantiate base class
        MyBase.New()

        ' Record the Info object between the constructor and the deserialization callback
        ' because if we set the values of fields that are declared with
        ' an initializer, the initializer will come along and overwrite the value
        ' after this constructor has been called
        mInfo = info

    End Sub

#Region "Serialization Implementation"


    ' Variable to store the serialization info between New() and OnDeserialization()
    <NonSerialized()> Private mInfo As SerializationInfo


    '*******************************************************************************
    ' GetObjectData: Serializes the object
    '                This takes care of all objects in the inheritance 
    '                hierarchy. Derived classes should only override this
    '                method to add extra data.
    '*******************************************************************************
    Protected Overridable Sub GetObjectData(ByVal info As SerializationInfo, ByVal context As StreamingContext) Implements ISerializable.GetObjectData

        ' Use the shared method to populate the SerializationInfo object
        SerializableObject.SerializeObject(Me, info)

    End Sub


    '*******************************************************************************
    ' OnDeserialization: Called when serialization is finished to complete the process
    '                    This takes care of all objects in the inheritance 
    '                    hierarchy. Derived classes should only override this
    '                    method to preform any extra initialization
    '*******************************************************************************
    Protected Overridable Sub OnDeserialization(ByVal sender As Object) Implements System.Runtime.Serialization.IDeserializationCallback.OnDeserialization

        ' Call the shared method to deserialize the object
        SerializableObject.DeserializeObject(Me, mInfo)

        ' Kill the recorded info object
        mInfo = Nothing

    End Sub




#End Region

#Region "Shared Methods"

    '*******************************************************************************
    ' SerializeObejct: Serializes all the private fields of an object and filters
    '                  out event delegates
    '*******************************************************************************
    Public Shared Sub SerializeObject(ByVal obj As Object, ByVal info As SerializationInfo)


        ' Local Variables
        Dim aMembersToSerialize As MemberInfo()

        ' Error handler
        Try

            ' Get a list of all fields in this object and derived objects
            ' that are to be serialized
            aMembersToSerialize = SerializableObject.GetSerializableMembers(obj.GetType)

            '  Loop around all fields and save their values
            For Each objMember As MemberInfo In aMembersToSerialize

                ' It is valid to serialize if it is in this array
                ' Derived Fields with the same name as base fields
                ' will automaticall be handled, so we don't need to
                ' worry about duplicates

                ' Determine if it is a filed or property
                If objMember.MemberType = MemberTypes.Field Then

                    Dim objField As FieldInfo = DirectCast(objMember, FieldInfo)
                    info.AddValue(objField.Name, objField.GetValue(obj))

                ElseIf objMember.MemberType = MemberTypes.Property Then

                    Dim objProperty As PropertyInfo = DirectCast(objMember, PropertyInfo)
                    info.AddValue(objProperty.Name, objProperty.GetValue(obj, Nothing))

                End If

            Next

        Catch ex As Exception

            ' Trace any errors
            Trace.WriteLine("Error during serialization: " & ex.Message)
            Throw New SerializationException("Error during Serialization. ", ex)

        End Try

    End Sub


    '*******************************************************************************
    ' DeserializeObject: Populates an object instance from a serialized instance
    '                    The object must be fully created for this method to be called
    '                    i.e. Don't call this from a constructor - instead call it
    '                    from IDeserializationCallback.OnDeserialization
    '*******************************************************************************
    <Security.Permissions.SecurityPermission(Security.Permissions.SecurityAction.Assert, Assertion:=True, SerializationFormatter:=True)> _
    Public Shared Sub DeserializeObject(ByVal obj As Object, ByVal info As SerializationInfo)

        ' Local Variables
        Dim aFieldsToDeserialize As MemberInfo()
        Dim aValues As Object()

        ' Error handler
        Try


            ' Get a list of all fields in this object and derived objects
            aFieldsToDeserialize = SerializableObject.GetSerializableMembers(obj.GetType)

            ' Loop around all fields and get their values from the info object
            aValues = DirectCast(Array.CreateInstance(GetType(Object), aFieldsToDeserialize.Length), Object())

            For nCount As Integer = 0 To aFieldsToDeserialize.Length - 1

                ' Determine if it is a field or property
                If aFieldsToDeserialize(nCount).MemberType = MemberTypes.Field Then

                    ' get the field
                    Dim objField As FieldInfo = DirectCast(aFieldsToDeserialize(nCount), FieldInfo)

                    ' Get the value of the field from the info object
                    aValues(nCount) = info.GetValue(objField.Name, objField.FieldType)

                ElseIf aFieldsToDeserialize(nCount).MemberType = MemberTypes.Property Then

                    ' get the property
                    Dim objProperty As PropertyInfo = DirectCast(aFieldsToDeserialize(nCount), PropertyInfo)

                    ' Get the value of the field from the info object
                    aValues(nCount) = info.GetValue(objProperty.Name, objProperty.PropertyType)

                End If

            Next

            ' Now use formatter services to populate this object's fields
            FormatterServices.PopulateObjectMembers(obj, aFieldsToDeserialize, aValues)

        Catch ex As Exception

            ' Trace errors
            Trace.WriteLine("Error during deserialization: " & ex.Message)
            Throw New SerializationException("Error during deserialization", ex)

        End Try

    End Sub


    '*******************************************************************************
    ' GetSerializableMembers: Returns an array of all fields in the type and base types
    '                         That are to be serialized.
    '                         It excludes delegates and event delegates
    '*******************************************************************************
    <Security.Permissions.SecurityPermission(Security.Permissions.SecurityAction.Assert, Assertion:=True, SerializationFormatter:=True)> _
    Private Shared Function GetSerializableMembers(ByVal PersistableType As System.Type) As MemberInfo()

        ' Local Variables
        Dim aAllMembers() As System.Reflection.MemberInfo
        Dim aSerilizableMembers As System.Collections.ArrayList

        '  Get all the serializable members
        aAllMembers = FormatterServices.GetSerializableMembers(PersistableType)

        aSerilizableMembers = New System.Collections.ArrayList

        ' Filter non-serializable fields and event delegates
        For Each objMember As MemberInfo In aAllMembers

            ' We're only interested in fields and properties
            If objMember.MemberType = MemberTypes.Field Then

                ' get the field
                Dim objField As FieldInfo = DirectCast(objMember, FieldInfo)

                ' If it has a NonSerialized Attribute or if it is an event delegate, skip it
                If (Not GetType(System.Delegate).IsAssignableFrom(objField.FieldType)) Then

                    ' Add the field as it is valid for serialization
                    aSerilizableMembers.Add(objField)

                End If

            ElseIf objMember.MemberType = MemberTypes.Property Then

                ' get the property
                Dim objProperty As PropertyInfo = DirectCast(objMember, PropertyInfo)

                ' if it is an event delegate, skip it
                If (Not GetType(System.Delegate).IsAssignableFrom(objProperty.PropertyType)) Then

                    ' Add the field as it is valid for serialization
                    aSerilizableMembers.Add(objProperty)

                End If

            End If

        Next objMember


        ' Return the array of persistable fields - need to convert to an array first
        Return DirectCast(aSerilizableMembers.ToArray(GetType(MemberInfo)), MemberInfo())

    End Function


#End Region

End Class