PHP Forms and User Input
The PHP $_GET and $_POST variables are used to retrieve information from forms, like user input.
PHP Form Handling
The most important thing to notice when dealing with HTML forms and PHP is
that any form element in an HTML page will automatically be available to your PHP scripts.
Example
The example below contains an HTML form with two input fields and a submit
button:
<html>
<body>
<form action="welcome.php" method="post">
Name: <input type="text" name="fname" />
Age: <input type="text" name="age" />
<input type="submit" />
</form>
</body>
</html>
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When a user fills out the form above and click on the submit button, the form data
is sent to a PHP file, called "welcome.php":
"welcome.php" looks like this:
<html>
<body>
Welcome <?php echo $_POST["fname"]; ?>!<br />
You are <?php echo $_POST["age"]; ?> years old.
</body>
</html>
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Output could be something like this:
Welcome John!
You are 28 years old. |
The PHP $_GET and $_POST functions will be explained in the next chapters.
Form Validation
User input should be validated on the browser whenever possible (by client
scripts). Browser validation is faster and reduces the server load.
You should consider server validation if the user input will be inserted into
a database. A good way to validate a form on the server is to post the form to
itself, instead of jumping to a different page. The user will then get the error
messages on the same page as the form. This makes it easier to discover the
error.
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