Marnus Norval Marnus Norval - 1 year ago 138
ASP.NET (C#) Question

I cant access <asp:textbox> value in code behind file

Good Morning

I have a webpage with a button pad on it. It is used at a gas station with bad network so everytime they click on the button to add a number to the textbox it will load forever so I changed the button clicks to javascript.

It works perfectly but now the code behind gets an empty value (Not null) when i retrieve the value from the textbox.

This is my code

The buttons used to add the numbers to the textbox
and the textbox

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="default.aspx.cs" Inherits="OVKWEBAPP.WebForm1" %>

<!DOCTYPE html>

<html xmlns="">
<head runat="server">


<link rel="stylesheet" type="text/css" href="mainstyle.css" />
<style type="text/css">
position: fixed;
top: 0;
left: 0;
/*background-color: black;*/
z-index: 99;
opacity: 0.8;
filter: alpha(opacity=80);
-moz-opacity: 0.8;
min-height: 100%;
width: 100%;

font-family: Arial;
font-size: 10pt;
border: 5px solid #67CFF5;
width: 200px;
height: 100px;
display: none;
position: fixed;
background-color: White;
z-index: 999;

<form id="form1" runat="server">
<asp:TextBox ID="txtRknr" runat="server" CssClass="txtBoxRknr" PlaceHolder="Rekening Nommer" Enabled="False" autocomplete="off" Width="175px"></asp:TextBox>
<input type="button" id="btnPad1" runat="server" value="1" class="buttonsb" onclick="input(this);"/>
<input type="button" id="btnPad2" runat="server" value="2" class="buttonsb" onclick="input(this);"/>
<asp:Button ID="btnMsg1" runat="server" Text="Gaan Voort" CssClass="buttonsa" OnClick="btnMsg1_Click" />

<script type="text/javascript">
function input(e) {
document.getElementById("<%=txtRknr.ClientID %>").value = document.getElementById("<%=txtRknr.ClientID %>").value + e.value;

And this is my code in the code behind file

protected void btnMsg1_Click(object sender, EventArgs e)
lblError.Text = "";
//string user = txtRknr.Text;
string user = ((TextBox)FindControl("txtRknr")).Text;
if(user == "")
//if (txtRknr.Text == "")

Basically all this needs to do is add an account number to a textbox from an button pad on the website.

After the account is added they would click on continue button and then the code behind checks if the textbox is empty if it is not empty it connects to database to check if it is valid.

But no matter how many numbers i add to the textbox it is still empty when i access it from code behind.

Answer Source

Enabled="False" means that your input field will have a disabled attribute. Disabled form elements do not get posted in HTML forms, which means that when you access it from the code-behind, it's using the default value of the textbox.

Try ReadOnly="True" instead of Enabled="False" if you don't want the field to be edited by hand.


I guess ASP.NET prevents you from reading the value from a ReadOnly=True textbox, to prevent you from doing exactly what you're trying to do. A <asp:HiddenField> creates an <input type="hidden">, which you should be able to write the value and have it posted properly to the codebehind.

Recommended from our users: Dynamic Network Monitoring from WhatsUp Gold from IPSwitch. Free Download