PHP
Processing form data
Learn to receive POST-submitted form data through $_POST.
Reading data with $_POST
When a form is sent with method="post", PHP gathers the fields in the $_POST superglobal. A field with name="email" shows up on the PHP side as $_POST['email']. To learn whether the form was submitted, you check the submit button name or $_SERVER['REQUEST_METHOD'].
Example: if ($_SERVER['REQUEST_METHOD'] === 'POST') { $name = $_POST['name'] ?? ''; echo "Hello " . $name; }. The ?? gives an empty string for a missing key, so the page does not error when opened before submission.
Detecting submission
A form page both shows the form and processes the data when it is submitted. To tell that the form was sent there are two common ways: check the submit button name with isset(), or read $_SERVER['REQUEST_METHOD'].
The second way is more robust: if ($_SERVER['REQUEST_METHOD'] === 'POST') { ... }. When this condition is true you read the form data; otherwise you only show the form. For CLI testing you can set $_SERVER['REQUEST_METHOD'] = 'POST'; by hand.
Exercise Receive form data with $_POST and print it
Set $_SERVER['REQUEST_METHOD'] = "POST";. Set $_POST['name'] = "Alex";. Inside if ($_SERVER['REQUEST_METHOD'] === "POST") write echo "Hello, " . $_POST['name'] . "!";.
Show example solution
First write $_SERVER['REQUEST_METHOD'] = "POST"; and $_POST['name'] = "Alex";. Then add if ($_SERVER['REQUEST_METHOD'] === "POST") { echo "Hello, " . $_POST['name'] . "!"; }.
Example solution:
<?php
// Receive form data with $_POST and print it
$_SERVER['REQUEST_METHOD'] = "POST";
$_POST['name'] = "Alex";
if ($_SERVER['REQUEST_METHOD'] === "POST") {
echo "Hello, " . $_POST['name'] . "!";
}
Test yourself
-
Read the name field from $_POST
$name = ____['name'] ?? "";
Show answer
$name = $_POST['name'] ?? "";
-
What is the most robust way to tell the form was submitted?
- Check if $_POST is empty
- Use isset($_POST['submit'])
- Check $_SERVER['REQUEST_METHOD'] === 'POST'
- Look with empty($_POST)
Show answer
Check $_SERVER['REQUEST_METHOD'] === 'POST' — Correct. The REQUEST_METHOD check does not depend on the submit button name; it is the most robust way.
-
Match the form handling concepts
- method="post"
- Data in the body
- $_POST['name']
- Value of name field
- REQUEST_METHOD
- Request method
- ?? ''
- Missing key default
Next lesson: Security with htmlspecialchars()
