How to use posted data in the same page


2020-05-29 PHP Web

GOAL

To post the input data and display it on the same page with PHP.

Environment

Windows10
XAMPP 7.4.10

Preparation

1. Change the PHP program

Create a new PHP file “index.php” to submit data. You can see the details of this program in “How To Run PHP in XAMPP“.

<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8">
	<title>test</title>
</head>
<body>
	<form action="posted.php" method="POST">
		<label>Input message：</label>
		<input type="text" name="message" />　<input type="submit" value="Submit!" />
	</form>
</body>
</html>

2. Set action = “”

The action specifies the file to call. If you won’t move the page, action should be “”.

Method

Method 1. Use $_SERVER[‘REQUEST_METHOD’]

$_SERVER[‘REQUEST_METHOD’] is the variable to store the requested method. It returns the called requested method when the page is requested.

<body>
	<?php
	if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    	echo "The input data is ".$message;
    }
    ?>
	<form action="" method="POST">
		<label>Input message：</label>
		<input type="text" name="message" />　<input type="submit" value="Submit!" />
	</form>
</body>

Method 2. Use $_POST directly

<body>
	<?php
	if ($_POST) {
    	echo "The input data is ".$_POST['message'];
    }
    ?>
	<form action="" method="POST">
		<label>Input message：</label>
		<input type="text" name="message" />　<input type="submit" value="Submit!" />
	</form>
</body>

The result is the same as above.

Method 3. Use isset($_POST[‘message’])

<body>
	<?php
	if ($_POST) {
    	echo "The input data is ".$_POST['message'];
    }
    ?>
	<form action="" method="POST">
		<label>Input message：</label>
		<input type="text" name="message" />　<input type="submit" value="Submit!" />
	</form>
</body>

The result is the same as above. The strong point of this method is that the existence of each keys of $_POST can be determined.