ASP.NET Validation Controls: Ensuring Data Integrity and User Experience

Learn how to use ASP.NET's built-in validation controls to easily implement robust data validation in your web forms. This tutorial covers key controls (RequiredFieldValidator, CompareValidator, RangeValidator, etc.), their properties, and how to integrate them for efficient and user-friendly input validation.

ASP.NET Validation Controls

Introduction to Validation

Data validation is crucial in web applications to ensure data integrity and a good user experience. ASP.NET provides several built-in validation controls that make it easy to check user input without writing a lot of custom code. You can also create custom validation if needed.

ASP.NET Validation Controls

Here are some of the key validation controls:

Validator Description
CompareValidator Compares the value of one input control to another (e.g., checking if two passwords match).
RangeValidator Checks if a value falls within a specified range (e.g., age between 18 and 100).
RegularExpressionValidator Uses regular expressions to validate input against a specific pattern (e.g., email address format).
RequiredFieldValidator Ensures that a field is not left empty.
ValidationSummary Displays a list of all validation errors on the page.

ASP.NET CompareValidator

The CompareValidator compares the value of an input control to another control using comparison operators (less than, equal to, greater than, etc.). It won't perform validation if the input field is empty.

CompareValidator Properties

The CompareValidator has many properties to customize its appearance and behavior. Here are a few key ones:

  • ControlToCompare: The ID of the control to compare against.
  • ControlToValidate: The ID of the control being validated.
  • ErrorMessage: The error message to display if validation fails.
  • Operator: The comparison operator to use (e.g., "LessThan", "EqualTo").
  • Other properties control appearance (e.g., BackColor, ForeColor, Font).

Example: CompareValidator

This example demonstrates using a CompareValidator to ensure that a "second value" is greater than a "first value".

compare_validator_demo.aspx (Example Code):

Code

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="compare_validator_demo.aspx.cs"
    Inherits="asp.netexample.compare_validator_demo" %>

First value: <asp:TextBox ID="firstval" runat="server" /><br />
Second value: <asp:TextBox ID="secondval" runat="server" /><br />

<asp:CompareValidator ID="CompareValidator1" runat="server" ControlToCompare="secondval"
    ControlToValidate="firstval" Display="Dynamic" ErrorMessage="Second value must be greater than the first value" ForeColor="Red"
    Operator="LessThan" Type="Integer"></asp:CompareValidator>