Difference between revisions of "PHP Session"
(Created page with "PHP Session Variables What is a PHP Session? When you work with an application, you open it, do some changes, and then you close it. This is much like a Session. The computer...") |
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| − | + | ==What is a PHP Session?== | |
| − | What is a PHP Session? | ||
When you work with an application, you open it, do some changes, and then you | When you work with an application, you open it, do some changes, and then you | ||
close it. This is much like a Session. The computer knows who you are. It knows | close it. This is much like a Session. The computer knows who you are. It knows | ||
| Line 6: | Line 5: | ||
problem: the web server does not know who you are or what you do, because the | problem: the web server does not know who you are or what you do, because the | ||
HTTP address doesn't maintain state. | HTTP address doesn't maintain state. | ||
| + | |||
Session variables solve this problem by storing user information to be used across | Session variables solve this problem by storing user information to be used across | ||
multiple pages (e.g. username, favorite color, etc). By default, session variables | multiple pages (e.g. username, favorite color, etc). By default, session variables | ||
| − | last until the user closes the browser. | + | last until the user closes the browser. So; Session variables hold information about one single user, and are available to |
| − | So; Session variables hold information about one single user, and are available to | ||
all pages in one application. | all pages in one application. | ||
| − | Start a PHP Session | + | |
| + | ==Start a PHP Session== | ||
A session is started with the session_start() function. | A session is started with the session_start() function. | ||
| + | |||
The code below should be at the very start of every page: | The code below should be at the very start of every page: | ||
| + | <syntaxhighlight lang=php> | ||
<?php | <?php | ||
// Start the session | // Start the session | ||
session_start(); | session_start(); | ||
?> | ?> | ||
| + | </syntaxhighlight> | ||
| − | Set PHP Session Variable Values | + | ==Set PHP Session Variable Values== |
Session variables are set with the PHP global variable: $_SESSION: | Session variables are set with the PHP global variable: $_SESSION: | ||
| + | |||
| + | <syntaxhighlight lang=php> | ||
<?php | <?php | ||
// Set session variables | // Set session variables | ||
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echo "Session variables are set."; | echo "Session variables are set."; | ||
?> | ?> | ||
| + | </syntaxhighlight> | ||
| − | Get PHP Session Variable Values | + | ==Get PHP Session Variable Values== |
Notice that session variables are not passed individually to each new page, instead | Notice that session variables are not passed individually to each new page, instead | ||
they are retrieved from the session we open at the beginning of each page using | they are retrieved from the session we open at the beginning of each page using | ||
‘session_start()’. This should be at the very start of the page. | ‘session_start()’. This should be at the very start of the page. | ||
| + | |||
Also notice that all session variable values are stored in the global $_SESSION | Also notice that all session variable values are stored in the global $_SESSION | ||
variable. You retrieve a session value using the name given: | variable. You retrieve a session value using the name given: | ||
| + | |||
| + | <syntaxhighlight lang=php> | ||
<?php | <?php | ||
session_start(); | session_start(); | ||
| Line 47: | Line 56: | ||
</body> | </body> | ||
</html> | </html> | ||
| + | </syntaxhighlight> | ||
Another way to show all the session variable values for a user session is to run the | Another way to show all the session variable values for a user session is to run the | ||
following code: | following code: | ||
| + | |||
| + | <syntaxhighlight lang=php> | ||
<?php | <?php | ||
session_start(); | session_start(); | ||
| Line 61: | Line 73: | ||
</body> | </body> | ||
</html> | </html> | ||
| + | </syntaxhighlight> | ||
| − | Modify a PHP Session Variable | + | ==Modify a PHP Session Variable== |
To change a session variable, just overwrite it: | To change a session variable, just overwrite it: | ||
| + | |||
| + | <syntaxhighlight lang=php> | ||
<?php | <?php | ||
session_start(); | session_start(); | ||
| Line 77: | Line 92: | ||
</body> | </body> | ||
</html> | </html> | ||
| + | </syntaxhighlight> | ||
| − | Destroy a PHP Session | + | ==Destroy a PHP Session== |
To remove all global session variables and destroy the session, use | To remove all global session variables and destroy the session, use | ||
session_unset() and session_destroy(): | session_unset() and session_destroy(): | ||
| + | |||
| + | <syntaxhighlight lang=php> | ||
<?php | <?php | ||
session_start(); | session_start(); | ||
| Line 95: | Line 113: | ||
</body> | </body> | ||
</html> | </html> | ||
| + | <syntaxhighlight lang=php> | ||
Revision as of 20:56, 15 September 2017
Contents
What is a PHP Session?
When you work with an application, you open it, do some changes, and then you close it. This is much like a Session. The computer knows who you are. It knows when you start the application and when you end. But on the internet there is one problem: the web server does not know who you are or what you do, because the HTTP address doesn't maintain state.
Session variables solve this problem by storing user information to be used across multiple pages (e.g. username, favorite color, etc). By default, session variables last until the user closes the browser. So; Session variables hold information about one single user, and are available to all pages in one application.
Start a PHP Session
A session is started with the session_start() function.
The code below should be at the very start of every page:
<?php
// Start the session
session_start();
?>
Set PHP Session Variable Values
Session variables are set with the PHP global variable: $_SESSION:
<?php
// Set session variables
$_SESSION["favcolor"] = "green";
$_SESSION["favanimal"] = "cat";
echo "Session variables are set.";
?>
Get PHP Session Variable Values
Notice that session variables are not passed individually to each new page, instead they are retrieved from the session we open at the beginning of each page using ‘session_start()’. This should be at the very start of the page.
Also notice that all session variable values are stored in the global $_SESSION variable. You retrieve a session value using the name given:
<?php
session_start();
?>
<!DOCTYPE html>
<html>
<body>
<?php
// Echo session variables that were set on previous page
echo "Favorite color is " . $_SESSION["favcolor"] . ".<br>";
echo "Favorite animal is " . $_SESSION["favanimal"] . ".";
?>
</body>
</html>
Another way to show all the session variable values for a user session is to run the following code:
<?php
session_start();
?>
<!DOCTYPE html>
<html>
<body>
<?php
print_r($_SESSION);
?>
</body>
</html>
Modify a PHP Session Variable
To change a session variable, just overwrite it:
<?php
session_start();
?>
<!DOCTYPE html>
<html>
<body>
<?php
// to change a session variable, just overwrite it
$_SESSION["favcolor"] = "yellow";
print_r($_SESSION);
?>
</body>
</html>
Destroy a PHP Session
To remove all global session variables and destroy the session, use session_unset() and session_destroy():
<syntaxhighlight lang=php> <?php session_start(); ?> <!DOCTYPE html> <html> <body> <?php // remove all session variables session_unset(); // destroy the session session_destroy(); ?> </body> </html> <syntaxhighlight lang=php>
