Visual Basic Serialization

[garry27]

Hi, I'm trying to serialize/deserialize data in vb. I've made a .dat file from a blank plain text file (not sure if this is suitable) which seems to connect ok, as do both the classes. Here's the code:

 

Imports Microsoft.VisualBasic.ControlChars
Imports System.IO
Imports System.Runtime.Serialization.Formatters.Binary


Public Class NewSalesPersonForm
    Inherits System.Windows.Forms.Form

    'dec object array
    Private mySalesPerson() As SalesPersonClass.SalesPersonClass   'namespaces required


    'dec primitive arrays

    'dec private vars
    Dim fullName As String
    Dim startDate As Date
    Dim nextIndex As Integer


    Private Sub NewSalesPersonForm_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

        'declare file stream and binary formatter
        Dim fs As New FileStream("sales-people.dat", FileMode.Open)
        Dim bf As New BinaryFormatter

        'read into array
        mySalesPerson = CType(bf.Deserialize(fs), SalesPersonClass.SalesPersonClass())

        'close file stream
        fs.Close()

        nextIndex = mySalesPerson.GetUpperBound(0)

    End Sub



    Private Sub btnExit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnExit.Click
        'Close()
    End Sub


    Private Sub btnAddSalesPerson_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnAddSalesPerson.Click

        'error checking

        mySalesPerson.pFullName = txtFullName.Text     'errors here
        mySalesPerson.pStartDate = cbDate.Text         'errors here



        'open filestream object to serial file
        Dim fs As New FileStream("sales-people.dat", FileMode.Create)

        'declare binary formatter object
        Dim bf As New BinaryFormatter

        'upload data from array into serial file
        bf.Serialize(fs, mySalesPerson)

        'close filestream
        fs.Close()


    End Sub
End Class





<Serializable()> Public Class SalesPersonClass

    'attributes
    Private fullName As String
    Private startDate As Date

    'empty constructor
    Public Sub New()
        fullName = ""
        startDate = ""
    End Sub

    'full constructor
    Public Sub New(ByVal vFullName As String, ByVal vStartDate As Date)
        fullName = vFullName
        startDate = vStartDate

    End Sub


    'properties
    Public Property pFullName() As String
        Get
            Return fullName
        End Get
        Set(ByVal Value As String)
            fullName = Value
        End Set
    End Property

    Public Property pStartDate() As String
        Get
            Return startDate
        End Get
        Set(ByVal Value As String)
            startDate = Value
        End Set
    End Property

End Class

 

The problem i think is that I'm trying to instantiate an empty object. It may also be because I'm not specifying an index in

mySalesPerson.pFullName

but when i do attach an index (0 to indicate start of array) I get an error that says "object reference not set to an instance of an object".

 

To be honest, I don't really know what's going on so any explanation on how to access objects contained in a dat file would be helpful as well.

 

Another thing is, I've seen three different ways to instantiate objects and not had much luck with any of them. They are:

 

    Private mySalesPerson As SalesPersonClass.SalesPersonClass 
    Private mySalesPerson As SalesPersonClass.SalesPersonClass() 
    Private mySalesPerson() As SalesPersonClass.SalesPersonClass 
    Private mySalesPerson() As SalesPersonClass.SalesPersonClass()

 

all of these are perfectly acceptable, gramatically, in vb and I've seen at least 3 of them used in various different examples. I assume the last 2 examples declare that you want to make an array of objects?!?!?!?

 

[garry27]

Any ideas people?