Common validation patterns in PHP - Mini Project: Build & Apply

Common validation patterns

📖 Scenario: You are building a simple PHP script to validate user input from a form. The form collects a username and an email address. You want to check that the username is not empty and the email address is in a valid format.

🎯 Goal: Create a PHP script that validates a username and an email address using common validation patterns. You will first set up the input data, then configure validation rules, apply the validation logic, and finally output the validation results.

📋 What You'll Learn

Create variables for username and email with exact values

Create a variable to hold an empty errors array

Use if statements to check if username is empty and if email is valid using filter_var

Print the errors array or a success message

💡 Why This Matters

🌍 Real World

Validating user input is essential in web forms to ensure data is correct and safe before saving or processing.

💼 Career

Understanding common validation patterns is important for backend developers, PHP programmers, and anyone working with user data.

1

DATA SETUP: Create input variables

Create two variables: $username with the value "john_doe" and $email with the value "[e-mail]".

PHP

<?php
// Your code here

Need a hint?

Use the = operator to assign the exact string values to the variables.

2

CONFIGURATION: Create an errors array

Create an empty array called $errors to store validation error messages.

PHP

<?php
$username = "john_doe";
$email = "[e-mail]";
// Your code here

Need a hint?

Use [] to create an empty array in PHP.

3

CORE LOGIC: Validate username and email

Use if statements to check if $username is empty and if $email is not a valid email using filter_var with FILTER_VALIDATE_EMAIL. If invalid, add error messages to $errors array using $errors[] = "message";.

PHP

<?php
$username = "john_doe";
$email = "[e-mail]";
$errors = [];
// Your code here

Need a hint?

Use empty() to check if a string is empty and filter_var() with FILTER_VALIDATE_EMAIL to check email format.

4

OUTPUT: Display validation results

Use if to check if $errors array is empty. If empty, print "Validation passed!". Otherwise, print each error message on a new line using a foreach loop.

PHP

<?php
$username = "john_doe";
$email = "[e-mail]";
$errors = [];

if (empty($username)) {
    $errors[] = "Username cannot be empty.";
}

if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
    $errors[] = "Email is not valid.";
}

// Your code here

Need a hint?

Use empty() to check if the errors array has no elements. Use foreach to print each error if any.