PHP Forms Required Fields

📝 PHP Forms – Required Fields Tutorial

When creating HTML forms, some fields may be mandatory, meaning the user must fill them before submitting. In PHP, you can validate these fields using server-side validation to ensure data integrity and security.

1️⃣ HTML Form with Required Fields

<form method="post" action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]); ?>">
Name: <input type="text" name="name">
<span style="color:red"><?php echo $nameErr; ?></span><br><br>

Email: <input type="text" name="email">
<span style="color:red"><?php echo $emailErr; ?></span><br><br>

Gender:
<input type="radio" name="gender" value="Male"> Male
<input type="radio" name="gender" value="Female"> Female
<span style="color:red"><?php echo $genderErr; ?></span><br><br>

<input type="submit" name="submit" value="Submit">
</form>

Name: <input type="text" name="name">

Email: <input type="text" name="email">

Gender:

<input type="radio" name="gender" value="Male"> Male

<input type="radio" name="gender" value="Female"> Female

</form>

2️⃣ PHP Script to Validate Required Fields

<?php
$name = $email = $gender = "";
$nameErr = $emailErr = $genderErr = "";

if ($_SERVER["REQUEST_METHOD"] == "POST") {

// Validate Name
if (empty($_POST["name"])) {
$nameErr = "Name is required";
} else {
$name = test_input($_POST["name"]);
}

// Validate Email
if (empty($_POST["email"])) {
$emailErr = "Email is required";
} else {
$email = test_input($_POST["email"]);
if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
$emailErr = "Invalid email format";
}
}

// Validate Gender
if (empty($_POST["gender"])) {
$genderErr = "Gender is required";
} else {
$gender = test_input($_POST["gender"]);
}
}

// Function to sanitize input
function test_input($data) {
$data = trim($data); // Remove extra spaces
$data = stripslashes($data); // Remove backslashes
$data = htmlspecialchars($data); // Convert special characters
return $data;
}
?>

<?php

$name = $email = $gender = "";

$nameErr = $emailErr = $genderErr = "";

if ($_SERVER["REQUEST_METHOD"] == "POST") {

// Validate Name

if (empty($_POST["name"])) {

$nameErr = "Name is required";

} else {

$name = test_input($_POST["name"]);

}

// Validate Email

if (empty($_POST["email"])) {

$emailErr = "Email is required";

} else {

$email = test_input($_POST["email"]);

if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {

$emailErr = "Invalid email format";

}

// Validate Gender

if (empty($_POST["gender"])) {

$genderErr = "Gender is required";

} else {

$gender = test_input($_POST["gender"]);

}

// Function to sanitize input

function test_input($data) {

$data = trim($data); // Remove extra spaces

$data = stripslashes($data); // Remove backslashes

$data = htmlspecialchars($data); // Convert special characters

return $data;

}

3️⃣ Display Submitted Data (If Valid)

4️⃣ Key Points

empty() Function: Checks if a field is blank.
Sanitization: Use trim(), stripslashes(), and htmlspecialchars() to secure input.
Error Messages: Display next to the fields for better UX.
Sticky Fields: Preserve user input after form submission.

5️⃣ Optional HTML5 Required Attribute

You can also use the HTML5 required attribute to prevent empty fields before submitting:

✅ Note: Always validate on the server-side, as users can bypass HTML5 validation.

🏁 Summary

Required fields cannot be left empty.
Use PHP empty() to validate server-side.
Display error messages to guide users.
Always sanitize and validate user input for security.

PHP Forms Required Fields