problem in work with datagridviewcolumns class

[pooya1072]

hi friends

i create a new class that inherits datagridview . my main purpose is to add a new property to all columns of this new datagridview .
my professor want that i do this in the form below . i explain to you all the steps and my problem :
1- i create a new class of DatagridviewColumns :

Public Class MyDatagridviewColumn
    Inherits DataGridViewColumn
    Dim MName As String
    Public Property MyNewProperty As String
        Get
            Return MName
        End Get
        Set(ByVal value As String)
            MName = value
        End Set
    End Property
End Class

2- i create a new class inherits of datagridview :

Public Class MyDatagriedview
    Inherits DataGridView

    Dim C1 As MyDatagridviewColumn
    Dim CC1 As DataGridViewColumnCollection

    Public Shadows Property Columns(ByVal Index As Integer) As MyDatagridviewColumn
        Get
            Return C1
        End Get
        Set(ByVal value As MyDatagridviewColumn)
            C1 = value
        End Set
    End Property
    Public Shadows Property Columns As DataGridViewColumnCollection
        Get
            Return CC1
        End Get
        Set(ByVal value As DataGridViewColumnCollection)
            CC1 = value
        End Set
    End Property
    Public Sub Initialize()
        C1 = New MyDatagridviewColumn
        CC1 = New DataGridViewColumnCollection(Me)
    End Sub
    Sub New()
        Initialize()
    End Sub
End Class

3- now i add it to my form in runtime and add on example column to it :

Public Class Form1
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim mdgv As New MyDatagriedview
        mdgv.Columns.Add("c1", "c2")
        Me.Controls.Add(mdgv)
    End Sub
End Class

but it dont work . form is load and a datagridview with no column is appear . what and where is the problem?

[dunfiddlin]

I hardly know where to begin. I'm not sure why no column is shown but it's obvious why it's not one of your custom columns. Your MyDatagriedview class (and you couldn't spare the time to correct the typo?) doesn't actually do anything new at all. If you want .Columns.Add() to add a different kind of column (I'll leave aside my doubts about what you gain from this alleged customisation that you don't get from the columns header or tag properties!) then you need to override or overload that method. Shadowing the two properties as you have does nothing useful at all and probably explains why the control comes up empty.

[pooya1072]

sure .. now i explain all i need to do and please you show me the way ...
i have a datagridview that it bind to a sql database via a Datatable . all rows and columns add to datagridview with DataAdapter.Fill command .
so i want all columns like Columns(0) or Columns(1) or .... has a New Property For example Named MyNewProperty .
how can i do this ? is it possible?

[dunfiddlin]

You're really overthinking this. All you are doing is adding a new column style to those that are available to the DataGridView control. So once you have created you column class ....

Public Class MyDatagridviewColumn
    Inherits DataGridViewTextBoxColumn ' NB. the change here DataGridViewColumn is a generic class which has no cell template
    Dim MName As String
    Public Property MyNewProperty As String
        Get
            Return MName
        End Get
        Set(ByVal value As String)
            MName = value
        End Set
    End Property
End Class

... you simply add it to the datagridview in the normal way.

Dim mdgCol As New MyDatagridviewColumn
        mdgCol.MyNewProperty = "My New Column Property"
        mdgCol.HeaderText = mdgCol.MyNewProperty
        DataGridView1.Columns.Add(mdgCol)

There really is no need to change the DGV control itself in any way.

[pooya1072]

thanks ... i will try to use your guide