How to extract value of textbox used in datalist

[upcomingaman]

I am developing a add to cart page

I'm using using DataList to display items and a small TextBox with default value "1" to show quantity. if user change this value to some other integer then the new value should be needed on next page

I am finding it difficult that how to extract value from TextBox that i have used inside DataList


-------HERE IS MY CODE------

<asp:DataList ID="ProductDataList"   DataSourceID ="ProductDataSource"  RepeatColumns="3"  RepeatDirection="Horizontal" runat="server"  >
  <ItemTemplate>         
    <div>                   
      <div style="margin-top:10px;width:190px;height:auto;text-align:inherit">
        <a href='<%# Page.ResolveUrl("Productdetails.aspx?ISBNNumber="+ Eval("ISBN")+"&ProductID="+Eval("ProductId")) %>'>
          <img src='<%# Eval("Product_Image") %>' alt="product image" width="100px" height="120px" />
        </a>
      </div>
 
      <div>
        <div style="width:190px;height:50px" >
          <a  style=" font-size:11px;color:#068EA8;background-color:White;" href='<%# Page.ResolveUrl("Productdetails.aspx?ISBNNumber="+ Eval("ISBN")+"&ProductID="+Eval("ProductId")) %>' >
          <%# Eval("Product_Name") %> 
          </a>
        </div>
 
        <span style="font-size:12px;font-weight:bolder;color:#8B4513;background-color:White;" >
          <strong>Price: </strong>
          <%# Eval("Price", "{0:c}")%>
       </span>
      </div>         
 
      <div>
        <table style="margin-left:70px;" >
          <tr>
            <td >
              <asp:TextBox ID="TextBox1"  Text="1" AutoPostBack="true" Width="14px" Height="18px" runat="server"></asp:TextBox>
            </td>
            <td style="width:5px;">
            </td>
            <td>
              <a href='<%# Page.ResolveUrl("basket.aspx?ISBNNumber="+ Eval("ISBN")+"&ProductID="+Eval("ProductId"))%>'>
                <img  src='images/add_tocart.gif' alt="ADD TO CART"   />
              </a>             
            </td>
          </tr>
        </table>
      </div>
 
      <div>
        <a style="font-size:11px;color:#068EA8;background-color:White;text-decoration:underline" href='<%# Page.ResolveUrl("Productdetails.aspx?ISBNNumber="+ Eval("ISBN")+"&ProductID="+Eval("ProductId")) %>'>Click for Details</a>
      </div>
 
    </div>                         
  </ItemTemplate>
</asp:DataList>
 

[Frinavale]

Implement a method that will handle all of the TextBox TextChanged events.

(VB.NET)

Protected Sub text_change(ByVal sender As Object, ByVal e As EventArgs)
 
End Sub

(C#)

protected void text_change(object sender, EventArgs e)
{
}

In the asp.net code for the TextBox in your TemplateItem for your DataGrid, set the OnTextChanged attribute to the method that you just implemented.

<asp:TextBox ID="Quantity" 
             runat="server" 
             AutoPostBack="true" 
             OnTextChanged="text_change"
             Width="14px" 
             Height="18px" 
             Text='<%# Eval("Quantity") %>'>
</asp:TextBox>

So now, when the user changes the Text in the TextBox the page will post back to the server and the TextChanged method that you implemented will be called.

The sender parameter for the TextChanged method will be the TextBox whose Text Property changed.

Cast the sender parameter into a TextBox so that you can retrieve the Text from it.
(VB.NET)

    Protected Sub text_change(ByVal sender As Object, ByVal e As EventArgs)
        Dim txtBox As TextBox = TryCast(sender, TextBox)
        Dim qty As Integer
        Integer.TryParse(txtBox.Text, qty)
    End Sub
 

(C#)

protected void text_change(object sender, EventArgs e)
{
  TextBox txtBox = (TextBox)sender;
  int qty;
  int.TryParse(txtBox.Text, out qty);
}

Now you have the quantity that the user supplied.

You have to update your data source for the DataList so that the user's changes are actually accepted.

Before you can do this you need to retrieve the Item whose quantity changed.

To do that use the TextBox's BindingContainer property. This will be the DataListItem that the TextBox belongs to.

If you add an invisible asp.net Label to your TemplateItem that is bound to the ID of the product, you can retrieve the ID of the item from the DataListItem using the FindControl("labelID") method.

<asp:Label ID="ProductId" runat="server" Text='<%# Eval("ProductId") %>' Style="display: none" />

(VB.NET)

Protected Sub text_change(ByVal sender As Object, ByVal e As EventArgs)
        Dim txtBox As TextBox = TryCast(sender, TextBox)
        Dim listItem As DataListItem = TryCast(txtBox.BindingContainer, DataListItem)
        Dim pidLabel As Label = listItem.FindControl("ProductId")
 
        Dim pid As Integer
        Integer.TryParse(pidLabel.Text, pid)
 
        Dim qty As Integer
        Integer.TryParse(txtBox.Text, qty)
        'now you need to update your data source using the ProductId
    End Sub
 

(C#)

 protected void text_change(object sender, EventArgs e)
{
  TextBox txtBox = (TextBox)sender;
  DataListItem listItem = (DataListItem)txtBox.BindingContainer;
  Label pidLabel = (Label) listItem.FindControl("ProductId");
  int pid;
  int.TryParse(pidLabel.Text, out pid);
  int qty;
  int.TryParse(txtBox.Text, out qty);
  //now you need to update your data source using the ProductId
}

Here is a full working example.
(ASP.NET code to hook up to a VB.NET code behind)

<%@ Page Language="vb" AutoEventWireup="false" CodeBehind="Default.aspx.vb" Inherits="WebApplication1._Default" Title="Products Page" %>
 
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
 
</head>
<body>
    <form id="form1" runat="server">
      <asp:DataList ID="ProductDataList" RepeatColumns="3" RepeatDirection="Horizontal"
    runat="server">
        <ItemTemplate>
          <div style="margin-top: 10px; width: 190px; height: auto; text-align: inherit">
            <asp:Label ID="ProductId" runat="server" Text='<%# Eval("ProductId") %>' Style="display: none" />
            <a href='<%# Page.ResolveUrl("Productdetails.aspx?ISBNNumber="+ Eval("ISBN")+"&ProductID="+Eval("ProductId")) %>'>
                <img src='<%# Eval("Product_Image") %>' alt="product image" width="100px" height="120px" />
            </a>
            <div style="width: 190px;">
                <a style="font-size: 11px; color: #068EA8; background-color: White;" href='<%# Page.ResolveUrl("Productdetails.aspx?ISBNNumber="+ Eval("ISBN")+"&ProductID="+Eval("ProductId")) %>'>
                    <%# Eval("Product_Name") %>
                </a>
                <div>
                    <span style="font-size: 12px; font-weight: bolder; color: #8B4513; background-color: White;">
                        <strong>Price: </strong>
                        <%# Eval("Price", "{0:c}")%>
                    </span>
                    <asp:TextBox ID="Txt_Quantity" Text='<%# Eval("Quantity") %>' OnTextChanged="text_change"
                        AutoPostBack="true" runat="server" Style="margin: 0px,5px; width: 24px; height: 18px;"></asp:TextBox>
                    <div>
                        <strong>Cost:</strong>
                        <%#Eval("Cost", "{0:c}")%>
                    </div>
                </div>
                <div>
                    <a href='<%# Page.ResolveUrl("basket.aspx?ISBNNumber="+ Eval("ISBN")+"&ProductID="+Eval("ProductId"))%>'>
                        <img src='images/add_tocart.gif' alt="ADD TO CART" />
                    </a>
                    <br />
                    <a style="font-size: 11px; color: #068EA8; background-color: White; text-decoration: underline"
                        href='<%# Page.ResolveUrl("Productdetails.aspx?ISBNNumber="+ Eval("ISBN")+"&ProductID="+Eval("ProductId")) %>'>
                        Click for Details</a>
                </div>
            </div>
          </div>
        </ItemTemplate>
      </asp:DataList>
    </form>
</body>
</html>

If you want the ASP.NET code to hook up to a C# code behind then use the following <%Page %> definition:

<%@ Page  Language="C#" AutoEventWireup="true"
    CodeBehind="Default.aspx.cs" Inherits="WebApplication1._Default" Title="Products Page" %>

(VB.NET Page Code)

Partial Public Class _Default
    Inherits System.Web.UI.Page
    Private _products As List(Of Product)
 
    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        GenerateList()
    End Sub
 
    Private Sub GenerateList()
        If Session("_products") Is Nothing Then
            _products = New List(Of Product)
            For i As Integer = 0 To 9
                Dim newProduct As New Product(String.Format("{0} {1}", "Product", i), i, String.Format("{0}{0}{0}-{0}-{0}{0}-{0}{0}{0}{0}{0}{0}-{0}", i), CType(i,Double))
                _products.Add(newProduct)
            Next
        Else
            _products = DirectCast(Session("_products"), List(Of Product))
        End If
    End Sub
 
 
    Private Sub Page_PreRender(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.PreRender
        Session("_products") = _list
        ProductDataList.DataSource = _list
        ProductDataList.DataBind()
    End Sub
 
    Protected Sub TxtChanged(ByVal sender As Object, ByVal e As EventArgs)
        Dim txtBox As TextBox = TryCast(sender, TextBox)
        Dim listItem As DataListItem = TryCast(txtBox.BindingContainer, DataListItem)
        Dim pidLabel As Label = listItem.FindControl("ProductId")
        Dim pid As Integer
        Integer.TryParse(pidLabel.Text, pid)
 
        Dim p As Product = _list.Find(Function(item) item.ProductId = pid)
        If p IsNot Nothing Then
            Integer.TryParse(txtBox.Text, p.Qty)
        End If
    End Sub
End Class
 

(C# Page Code)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
 
namespace WebApplication1
{
    public partial class _Default : System.Web.UI.Page
    {
        private List<Product> _products;
        protected void Page_Load(object sender, EventArgs e)
        {
            if (IsPostBack == false)
            {
                _products = new List<Product>();
                for (int i = 1; i < 11; i++)
                {
                    Product newProduct = new Product(String.Format("{0} {1}", "Product", i), i, String.Format("{0}{0}{0}-{0}-{0}{0}-{0}{0}{0}{0}{0}{0}-{0}", i), (double)i);
                    _products.Add(newProduct);
                }
 
            }
            else
            {
                _products = (List<Product>)Session["_products"];
            }
        }
 
        protected void text_change(object sender, EventArgs e)
        {
            TextBox txtBox = (TextBox)sender;
            DataListItem listItem = (DataListItem)txtBox.BindingContainer;
            Label pidLabel = (Label) listItem.FindControl("ProductID");
            int pid;
            int.TryParse(pidLabel.Text, out pid);
            Product p = _products.Find((ep) => ep.ProductId == pid);
            if (p != null)
            {   int qty;
                int.TryParse(txtBox.Text, out qty);
                p.Quantity = qty;
            }
 
        }
        protected void Page_PreRender(object sender, EventArgs e)
        {
            Session["_products"] = _products;
            ProductDataList.DataSource = _products;
            ProductDataList.DataBind();
        }
    }
 
}
 

Product class used as data for the data source
(VB.NET)

Public Class Product
    Private _name As String
    Private _id As Integer
    Private _isbn As String
    Private _qty As Integer
    Private _price As Double
 
    Public Property Product_Name() As String
        Get
            Return _name
        End Get
        Set(ByVal value As String)
            _name = value
        End Set
    End Property
    Public Property ProductId() As Integer
        Get
            Return _id
        End Get
        Set(ByVal value As Integer)
            _id = value
        End Set
    End Property
    Public Property ISBN() As String
        Get
            Return _isbn
        End Get
        Set(ByVal value As String)
            _isbn = value
        End Set
    End Property
    Public Property Price() As Double
        Get
            Return _price
        End Get
        Set(ByVal value As Double)
            _price = value
        End Set
    End Property
    Public Property Quantity() As Integer
        Get
            Return _qty
        End Get
        Set(ByVal value As Integer)
            _qty = value
        End Set
    End Property
    Public ReadOnly Property Cost() As Double
        Get
            Return Price * Qty
        End Get
    End Property
 
    Public Sub New(ByVal name As String, ByVal id As Integer, ByVal price As Double)
        _id = id
        _name = name
        _qty = 0
        _price = price
    End Sub
End Class

(C#)

  public class Product
    {
        public string Product_Name { get; set; }
        public int ProductId { get; set; }
        public string ISBN { get; set; }
        public double Quantity { get; set; }
        public double Price { get; set; }
        public  double Cost 
        {
            get { return this.Quantity * this.Price; } 
        }
        public string Product_Image { get; set; }
 
        public Product(string name, int id, string isbn, double price)
        {
            this.Quantity = 0;
            this.Product_Name = name;
            this.ProductId = id;
            this.ISBN = isbn;
            this.Price = price;
        }
    }

[upcomingaman]

Thanks for your reply...
but m using C# coding and you had given me solution in VB.
Please provide me solution in C#
Thanks in adv.

[Frinavale]

I took the time to go through your incomplete code and provide you with a thorough answer.

The least you could do is attempt to read read my answer to understand what I was doing...that way you could take the concepts that I posted and attempt to implement the solution on your own.

The absolute VERY least you could do is search for a website (like this one) that will convert C# to VB.NET and vice versa.

By the way, while my answer includes a working solution that is roughly based on your code, it will not work as-is for your specific application you if copy & paste the solution into your application. The code example that I posted is meant as a guideline to help you understand the concepts I talked about in my answer.

Edit: I added the C# syntax version of the solution.

-Frinny

[NeoPa]

@upcomingaman

Please see my PM (Private Message).

[upcomingaman]

No problem Sir....thanks a lot for your support. I will try to Implement this logic in my project using C# after going through your hint in VB

[upcomingaman]

I am trying to extract value of textbox used in Datalist on textchange event but when i run this coe it gives me an error
"Index was out of range. Must be non-negative and less than the size of the collection.
Parameter name: index "

<asp:DataList ID="ProductDataList"   DataSourceID ="ProductDataSource"  RepeatColumns="3"  RepeatDirection="Horizontal" runat="server" >
  <ItemTemplate>
    <div >
      <div style="margin-top:10px;width:190px;height:auto;text-align:inherit">
        <a href='<%# Page.ResolveUrl("Productdetails.aspx?ISBNNumber="+ Eval("ISBN")+"&ProductID="+Eval("ProductId")) %>'>
          <img src='<%# Eval("Product_Image") %>' alt="product image" width="100px" height="120px" />
        </a>
      </div>
      <div>
        <div style="width:190px;height:50px" >
          <a  style=" font-size:11px;color:#068EA8;background-color:White;" href='<%# Page.ResolveUrl("Productdetails.aspx?ISBNNumber="+ Eval("ISBN")+"&ProductID="+Eval("ProductId")) %>' >
        <%# Eval("Product_Name") %>
          </a>
          <div>
            <span style="font-size:12px;font-weight:bolder;color:#8B4513;background-color:White;" >
              <strong>Price: </strong>
            <%# Eval("Price", "{0:c}")%>
            </span>
          </div>
 
          <div>
            <table style="margin-left:70px;" >
              <tr>
                <td >      
                  <asp:TextBox ID="TextBox1"  Text="1"  OnTextChanged="text_change"  AutoPostBack="true" Width="14px" Height="18px" runat="server"></asp:TextBox>
                </td>
                <td style="width:5px;">
                </td>
                <td>
                  <a href='<%# Page.ResolveUrl("basket.aspx?ISBNNumber="+ Eval("ISBN")+"&ProductID="+Eval("ProductId"))%>'>
                    <img  src='images/add_tocart.gif' alt="ADD TO CART"   />
                  </a>
                </td>
              </tr>
            </table>
          </div>
          <div>
            <a style="font-size:11px;color:#068EA8;background-color:White;text-decoration:underline" href='<%# Page.ResolveUrl("Productdetails.aspx?ISBNNumber="+ Eval("ISBN")+"&ProductID="+Eval("ProductId")) %>'>Click for Details</a>
          </div>
        </div>
 
  </ItemTemplate>
</asp:DataList>
 
 

protected void text_change(object sender, EventArgs e)
{
  string noofbooks = Server.HtmlEncode(((TextBox)ProductDataList.Items[Product  DataList.SelectedIndex].FindControl("TextBox1")).Text);
}

Please provide me some help
Thanks in adv

[Frinavale]

I don't think you actually read my previous post....
But, at least you showed that you've made an attempt to solve your problem.

Your text_changed method handles the TextBox1's OnTextChanged event.

Using the FindControl method on the ProductDataList to retrieve the TextBox won't work in the text_changed method because there are multiple TextBox1's in the ProductDataList method. It doesn't really make sense to try to do this in the first place...

Since the text_changed handles the OnTextChanged event for the TextBox, you know that the sender parameter is the TextBox1 that you need to retrieve the value from.

So, change your code to cast the sender into a TextBox and retrieve the text from it:

protected void text_change(object sender, EventArgs e)
{
  TextBox txtBox = (TextBox)sender;
  string noofbooks = txtBox.Text;
}

-Frinny