Validating user input e.g, required fields, email format
User input validation in PHP programming helps programmers validate form elements to ensure that user input used in the current form is valid and in the proper format. This method helps prevent form element errors, maintain a consistent form user experience, and increase form element security by providing protection against malicious form activity from user input.
Form input validation in PHP programming can be used in both client-side HTML5 and JavaScript programming, as well as in server-side PHP programming. Server-side validation is crucial when validating form elements, as it can determine whether form data is validated in the proper order. This allows user input to bypass client-side validation.
Main types of form element validation in PHP.
- Required field – This ensures that required user form inputs must fill in required fields.
- Format validation – This ensures that user inputs in the existing form properly match a specific format, such as email ID, phone number, etc.
- Boundary and length validation – This ensures that user inputs in the existing form must be within a particular length or range, such as the length of a user password.
- Custom validation – This allows the user to validate additional elements in the form, such as validating a user name or custom input.
HTML5 form validation is a client-side process in PHP programming.
In PHP programming, HTML5 uses built-in form element validation through attributes such as minimum length, maximum length, form pattern, and use form element type. It helps to quickly validate elements under simple conditions before sending form data to a dedicated web server.
Example of HTML5 required form field and email element validation.
<html>
<body>
<h1>Form Element Validation</h1>
<form action=”process_form.php” method=”POST”>
<label for=”employeename”>Employee Name</label>
<input type=”text” id=”employeename” name=”employeename” required><br><br>
<label for=”employeeemail”>Employee Email</label>
<input type=”email” id=”employeeemail” name=”employeeemail” required><br><br>
<label for=”password”>Password (at least 12 characters) </label>
<input type=”password” id=”password” name=”password” minlength=”12″ required><br><br>
<input type=”submit” value=”Submit”>
</form>
</body>
</html>
HTML5 required Form Field Explanation.
- Required field – This determines whether a form element field must be filled in before submitting the current form element.
- type=”email” – This determines whether the form input is in a valid email format or not.
- minlength=”12″ – This determines whether the form password entered by the employee must be at least 12 characters long and contain a combination of numbers, alphabets, special symbols, etc.
Server-side form element validation in PHP programming.
The HTML5 web development environment provides client-side form element validation features. Server-side validation of all form fields used in the form is mandatory, as these can be used by users to bypass client-side checks.
Example of form element validation in PHP.
<html>
<body>
<h1>Html Form Post Element Validation</h1>
<form action=”process_form.php” method=”POST”>
<label for=”employeename”>Employee Name</label>
<input type=”text” id=”employeename” name=”employeename” required><br><br>
<label for=”employeeemail”>Employee Email</label>
<input type=”email” id=”employeeemail” name=”employeeemail” required><br><br>
<label for=”password”>Password (at least 12 characters) </label>
<input type=”password” id=”password” name=”password” minlength=”12″ required><br><br>
<input type=”submit” value=”Submit”>
</form>
</body>
</html>
Validation script in PHP programming (process_form.php).
<?php
if ($_SERVER[“REQUEST_METHOD”] == “POST”) {
//here it Initializes error array
$errors = [];
// here it used to Validate employeename form field (essential)
if (empty($_POST[’empoyeename’])) {
$errors[] = “Employeename is required”;
}
// here it check or Validate employee Email (required and valid email format type)
if (empty($_POST[’employeeemail’])) {
$errors[] = “Email is required”;
} elseif (!filter_var($_POST[’employeeemail’], FILTER_VALIDATE_EMAIL)) {
$errors[] = “You Enter Invalid email”;
}
// here it Validate employee Password (at least min length of 12 characters)
if (empty($_POST[’employeepassword’])) {
$errors[] = “Password is essential”;
} elseif (strlen($_POST[’employeepassword’]) < 12) {
$errors[] = “Password at least 12 characters length”;
}
// here it used to Check if there are any errors in form element validation
if (empty($errors)) {
// If in the code no errors, it immediately process the form and save to database
echo “Form element submitted”;
} else {
//if any issue or problem is Display the form errors
foreach ($errors as $error) {
echo “<p style=’color: blue;’>$error</p>”;
}
}
}
?>
Description of PHP form required field validation.
- empty() – This checks whether a field in the current form is empty. It is useful for required form fields.
- filter_var() and FILTER_VALIDATE_EMAIL – This validates whether the email entered by the user is in the correct format.
- strlen() – This checks the length of the password entered in the form to ensure that the password must be at least 12 characters long.
If there are any errors in the current form data, they are stored in the $errors array and displayed on the webpage. If no errors are found in the current form, the form is processed successfully.
Custom validation functions in forms.
In PHP programming, you can create custom form validation functions for specific overview conditions. For example, validating an employee’s phone number or employee name on a form.
Custom username validation example in PHP programming.
<?php
function isValidEmployeename($employeename) {
// Here it checks if the employee name contains only alphanumeric characters and is between 2 and 17 characters
if (preg_match(“/^[a-zA-Z0-9]{2,17}$/”, $employeename)) {
return true;
}
return false;
}
if ($_SERVER[“REQUEST_METHOD”] == “POST”) {
$employeename = $_POST[’employeename’];
if (!isValidEmployeename($employeename)) {
echo “<p style=’color: yellow;’>Please enter Employeename alphanumeric and between 2 and 17 characters in length</p>”;
}
}
?>
preg_match() – This function is used to match regular expressions. In this condition, it checks that the employee name must contain only alphanumeric characters and must be between 2 and 17 characters long.
Sanitizing form input.
Form validation checks whether the entered form data is correct, while form element sanitization removes harmful form data in any possible order. For example, sanitizing a string to remove special characters before saving it to the database protects against XSS (cross-site scripting) attacks.
Example of sanitizing form input.
<?php
// This is used to sanitize user input to remove harmful characters from the form element.
$employeename = filter_var($_POST[’employeename’], FILTER_SANITIZE_STRING);
// This is used to sanitize the employee email element.
$employeeemail = filter_var($_POST[’employeeemail’], FILTER_SANITIZE_EMAIL);
?>
FILTER_SANITIZE_STRING – This removes tags and special characters from the string in the current form element.
FILTER_SANITIZE_EMAIL – This properly sanitizes email addresses to keep them secure.
Redirect after submitting the form element.
After the form element is successfully processed, you can redirect the form user directly to another webpage, such as a form confirmation page or a form page with a form submission success message.
<?php
if (empty($errors)) {
// here it is used to redirect the user to a thank you form page
header(“Location – thank_you.php”);
exit();
}
?>
header() – This sets an HTTP header location to redirect the current form user to.
exit() – This ensures that no further program code should be executed after the form redirect.
Validation Processing form user input.
- Client-side validation – Use HTML5 form attributes such as form field required, element type, minimum length, and JavaScript to provide quick feedback to the form user.
- Server-side validation – Always validate form user input on the server using PHP $_GET, $_POST, etc. methods to prevent malicious or false form data from being processed in the current form.
- Sanitization – Always sanitize input to remove malicious form data from a form. For example, use the filter_var method.
- Custom validation – Create custom form element functions for particular form-specific needs. For example, employee name form, custom regular expression checks, etc.
