Asp.net 2.0 update problem

[tsubasa]

Hello Folks,

I have a shopping cart that is allowing me to add items to the shopping cart that is displayed using a GridView. The GridView has an update link that will allow a user to change the quantity, yet everytime I try to update I get the following error:

"Specified argument was out of the range of valid values. Parameter name:index.

Below is the GridView and the Classes that is generating the error. I have check the text that I am using and it matches the code in the book, yet I can't figure out why the bug is generating.

Regards,

-Tsu

<%@ Page Title="ACME Book Supply" Language="VB" MasterPageFile="~/MasterPage.master" AutoEventWireup="false" CodeFile="Cart.aspx.vb" Inherits="Cart" %>

<asp:Content ID="Content1" ContentPlaceHolderID="head" Runat="Server">
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">
<br />
<asp:GridView ID="GridView1" runat="server" 
    AutoGenerateColumns="false"
    EmptyDataText="Your shopping cart is empty."
    OnRowDeleting="GridView1_RowDeleting"
    OnRowEditing="GridView1_RowEditing"
    OnRowUpdating="GridView1_RowUpdating"
    OnRowCancelingEdit="GridView1_RowCancelingEdit">
    <Columns>
        <asp:BoundField DataField="ID"
            HeaderText="Product" ReadOnly="true">
            <HeaderStyle HorizontalAlign="Left" />
        </asp:BoundField>
         <asp:BoundField DataField="Name"
            HeaderText="Name" ReadOnly="true">
            <HeaderStyle HorizontalAlign="Left" />
        </asp:BoundField>
         <asp:BoundField DataField="Price"
            HeaderText="Price" ReadOnly="true"
            DataFormatString="{0:c}">
            <HeaderStyle HorizontalAlign="Left" />
        </asp:BoundField>
        <asp:BoundField DataField="Quantity"
            HeaderText="Quantity">
            <HeaderStyle HorizontalAlign="Left" />
        </asp:BoundField>
        <asp:BoundField DataField="Total"
            HeaderText="Total" ReadOnly="true"
            DataFormatString="{0:c}">
            <HeaderStyle HorizontalAlign="Left" />
        </asp:BoundField>
        <asp:CommandField EditText="Change"
            ShowDeleteButton="true"
            ShowEditButton="true">
            <ItemStyle BorderStyle="None" />
            <HeaderStyle BorderStyle="None" />
        </asp:CommandField>
    </Columns>
    </asp:GridView>
    <br /><br />
    <asp:Button ID="btnContinue" runat="server"
        OnClick="btnContinue_Click"
        Text="Continue Shopping" />&nbsp;
    <asp:Button ID="btnCheckOut" runat="server"
    PostBackUrl="~/CheckOut.aspx"
    Text="Check Out" />
</asp:Content>

[CART.ASPX.VB]

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)
        Catch ex As FormatException
            e.Cancel = True
        End Try
        GridView1.EditIndex = -1
        GridView1.DataBind()
    End Sub

[SHOPPINGCART.AS PX.VB]

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)
        Dim item As CartItem
        item = _cart(Index)
        item.Quantity = quantity
    End Sub

    Public Sub DeleteItem(ByVal index As Integer)
        _cart.RemoveAt(index)
    End Sub

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

End Class

[Frinavale]

Consider using the FindControl method to retrieve your TextBox from the GridViewRow.

For example:

TextBox  t = (TextBox)GridView1.Rows(e.Row.RowIndex).FindControl("TextBox1"));

You may not even have to go through the GridView1.Rows parameter. You could probably access the row using the sender parameter of the RowUpdating event:

TextBox  t = (TextBox)((GridViewRow) sender).FindControl("TextBox1"));

-Frinny

[tsubasa]

I will give this a try. Thanks for the technical advise.

-Tsu

[tsubasa]

Hello Frinny,

I think you wrote your code in C#, my code is in VB can you please provide the VB code. Thanks!

[Frinavale]

Try using tools like this online converter tool in the future. You will find that most code examples are in C#.

You can use DirectCast or CType to cast the objects into the types you expect.

Dim t As TextBox = DirectCast( DirectCast( sender,GridViewRow).FindControl("TextBox1"), TextBox)

Dim t As TextBox = CType( CType( sender,GridViewRow).FindControl("TextBox1"), TextBox)

-Frinny