How to use validator in this case is ASP.NET?

Question

I have two input text boxes which are decimal.

The sum of the two inputs cannot be more than 100. When input1 is 40, input2 cannot be more than 60.

I need to do everything in client side and need to allow client to enter any value. If the entered value is more than the limit, I need to show the validator error message:

Page.isValid = false

Now I have two separate validator for each input box but I don't know how to change the valueToCompare of two validators in client side.

Please advise,

Thanks

Jacob · Accepted Answer · 2009-07-07 05:36:45Z

You should look into using the CustomValidator control. Here's an article that walks you through using it.

Your code could look something like this:

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" 
    Inherits="WebApplication1._Default" %>
<!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">
    <title></title>
    <script type="text/javascript">
      function validateTextBoxen(sender, args) {
        // You'll have more thorough validation, I'm sure
        var value1 = parseFloat(
            document.getElementById('<%=textBox1.ClientID%>').value);
        var value2 = parseFloat(
            document.getElementById('<%=textBox2.ClientID%>').value);
        args.IsValid = (value1 + value2) < 100;
      }
    </script>
  </head>
  <body>
    <form id="form1" runat="server">
      <div>
        <asp:TextBox ID="textBox1" runat="server" />
        <asp:TextBox ID="textBox2" runat="server" />
        <asp:CustomValidator runat="server" EnableClientScript="true" 
          OnServerValidate="onCustomValidation" ID="customValidator" 
          ErrorMessage="Invalid!"
          SetFocusOnError="true" ClientValidationFunction="validateTextBoxen"/>
        <asp:Button runat="server" OnClick="button_Click"/>
        <asp:Literal runat="server" ID="placeholder" />
      </div>
    </form>
  </body>
</html>

Code-behind:

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
    {
        protected void onCustomValidation(
            object sender, ServerValidateEventArgs e)
        {
            float value1 = 0f;
            float value2 = 0f;
            if (!float.TryParse(textBox1.Text, out value1) 
                || !float.TryParse(textBox2.Text, out value2)
                || value1 + value2 > 100f)
            {
                e.IsValid = false;
            }
        }

        protected void button_Click(object sender, EventArgs args)
        {
            placeholder.Text = Page.IsValid ? "Valid" : "Invalid";
        }
    }
}

Robert Harvey · Accepted Answer · 2009-07-07 04:39:57Z

0

Nowadays the best way to validate HTML forms IMO is with a jQuery plugin like this one.

answered Jul 7, 2009 at 4:39

Robert Harvey

182k48 gold badges349 silver badges516 bronze badges

Comments

Varun Mahajan · Accepted Answer · 2009-07-07 05:01:46Z

0

On client side, on the click of button, use ClientClick property, and set it to javascript function name to validate the input

e.g.

<asp:Button ID="btnSubmit" OnClientClick=" return validate()" runat="server" Text="Submit" ></asp:Button>

And write a validate() function in javascript, which check the sum of both inputs

answered Jul 7, 2009 at 5:01

Varun Mahajan

7,35716 gold badges47 silver badges66 bronze badges

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