Serializasation

Jeg har følgende klasse som jeg ønsker at putte i en database, hvilket betyde Serializasation. Fejle pt er "Objektet skal implementere IConvertible."
Imports Microsoft.VisualBasic


Namespace Competitions

    Public Enum QuestionType


        DropDown
    End Enum

    <Serializable()> _
    Public Class Answer
        Private _answer As String = ""
        Public Property Text() As String
            Get
                Return _answer
            End Get
            Set(ByVal value As String)
                _answer = value
            End Set
        End Property

        ' ==========
        ' Constructors
        ' ==========
        Public Sub New(ByVal Answer As String)
            Me.Text = Answer
        End Sub

    End Class



    <Serializable()> _
    Public Class Question


        Private _answers As List(Of Answer) = New List(Of Answer)

        Private _type As QuestionType
        Public Property Type() As QuestionType
            Get
                Return _type
            End Get
            Set(ByVal value As QuestionType)
                _type = value
            End Set
        End Property

        Private _question As String
        Public Property Text() As String
            Get
                Return _question
            End Get
            Set(ByVal value As String)
                _question = value
            End Set
        End Property

        Public WriteOnly Property addAnswer() As String
            Set(ByVal value As String)
                _answers.Add(New Answer(value))
            End Set
        End Property

        Public ReadOnly Property GetAnswers() As List(Of Answer)
            Get
                Return _answers
            End Get
        End Property


     

        ' ==========
        ' Constructors
        ' ==========
        Public Sub New(ByVal Question As String, ByVal Type As QuestionType)
            Me.Text = Question
            Me.Type = Type
        End Sub

    End Class


    <Serializable()> _
    Public Class Competition

        Private _questions As List(Of Question) = New List(Of Question)

        Private _name As String
        Public Property Name() As String
            Get
                Return _name
            End Get
            Set(ByVal value As String)
                _name = value
            End Set
        End Property

        Private _headline As String = ""
        Public Property Headline() As String
            Get
                Return _headline
            End Get
            Set(ByVal value As String)
                _headline = value
            End Set
        End Property

        Private _language As String = "dk"
        Public Property Language() As String
            Get
                Return _language
            End Get
            Set(ByVal value As String)
                _language = value
            End Set
        End Property

        Private _teaser As String = ""
        Public Property Teaser() As String
            Get
                Return _teaser
            End Get
            Set(ByVal value As String)
                _teaser = value
            End Set
        End Property

        Private _body As String = ""
        Public Property Body() As String
            Get
                Return _body
            End Get
            Set(ByVal value As String)
                _body = value
            End Set
        End Property

        Private _publish As DateTime
        Public Property Publish() As DateTime
            Get
                Return _publish
            End Get
            Set(ByVal value As DateTime)
                _publish = value
            End Set
        End Property

        Private _finish As DateTime
        Public Property Finish() As DateTime
            Get
                Return _finish
            End Get
            Set(ByVal value As DateTime)
                _finish = value
            End Set
        End Property


        Public WriteOnly Property addQuestion() As Question
            Set(ByVal value As Question)
                _questions.Add(value)
            End Set
        End Property

        Public ReadOnly Property Questions() As List(Of Question)
            Get
                Return _questions
            End Get
        End Property

        ' ==========
        ' Constructors
        ' ==========
        Public Sub New()
        End Sub

    End Class
End Namespace