Error in executing action of deleting and updating data from GridView

[miss nadia]

I'm developing an e-commerce web-based system & have problem in Shopping Cart part. i.e. update quantity & delete item from cart. This is code-behind for my Cart.aspx. <pre> 'other code above Protected Sub GridView1_RowDeleting(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewDeleteEventArgs) Handles GridView1.RowDeleting cart.DeleteItem(e.RowIndex) 'error here GridView1.DataBind() End Sub Protected Sub GridView1_RowEditing(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewEditEventArgs) Handles GridView1.RowEditing GridView1.EditIndex = e.NewEditIndex GridView1.DataBind() End Sub Protected Sub GridView1_RowUpdating(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewUpdateEventArgs) Handles GridView1.RowUpdating Dim cell As DataControlFieldCell cell = GridView1.Rows(e.RowIndex).Controls(3) Dim t As TextBox = cell.Controls(0) Try Dim q As Integer q = Integer.Parse(t.Text) cart.UpdateQuantity(e.RowIndex, q) 'error here Catch ex As FormatException e.Cancel = True End Try GridView1.EditIndex = -1 GridView1.DataBind() End Sub Protected Sub GridView1_RowCancelingEdit(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewCancelEditEventArgs) Handles GridView1.RowCancelingEdit e.Cancel = True GridView1.EditIndex = -1 GridView1.DataBind() End Sub 'other code below </pre> The error saying that: Exception Details: System.NullReferenceException: Object reference not set to an instance of an object. Thanks for your help!

[Abhijit Jana]

miss nadia wrote:

cart.DeleteItem(e.RowIndex) 'error here

Where is that function ?

Best Regards ----------------- Abhijit Jana "Success is Journey it's not a destination"

[miss nadia]

That function is in ShoppingClass class.

[miss nadia]

this is the function in ShoppingCart class.

Imports Microsoft.VisualBasic
Imports System.Collections.Generic

Public Class ShoppingCart

Private \_cart As List(Of CartItem)

Public Sub New()
    \_cart = New List(Of CartItem)()
End Sub

Public Function GetItems() As List(Of CartItem)
    Return \_cart
End Function

Public Sub AddItem(ByVal id As String, ByVal name As String, ByVal price As Decimal)
    Dim itemFound As Boolean = False
    For Each Item As CartItem In \_cart
        If Item.ID = id Then
            Item.Quantity += 1
            itemFound = True
        End If
    Next
    If Not itemFound Then
        Dim item As CartItem
        item = New CartItem(id, name, price, 1)
        \_cart.Add(item)
    End If
End Sub

Public Sub UpdateQuantity(ByVal index As Integer, ByVal quantity As Integer)    'update quantity function
    Dim item As CartItem
    item = \_cart(index)
    item.Quantity = quantity
End Sub

Public Sub DeleteItem(ByVal index As Integer) 'delete item function
    \_cart.RemoveAt(index)
End Sub

Public ReadOnly Property Count() As Integer
    Get
        Return \_cart.Count
    End Get
End Property

End Class