PHP COOKIES AND SESSIONS
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Jun 17, 2023
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About This Presentation
Advanced Internet Programming
Slide Content
Chapter 5 Cookies and Session
Contents Cookies and Sessions Describe the stateless model Explain the concepts of maintaining state with sessions Create and Read data from sessions
What is a Cookie ? A cookie is often used to identify a user. A cookie is a small file that the server embeds on the user's computer. Each time the same computer requests a page with a browser, it will send the cookie too. With PHP, you can both create and retrieve cookie values.
Cookies are primarily used to store the user’s browsing history.
Create Cookies With PHP A cookie is created with the setcookie () function . Syntax: setcookie (name, value, expire, path, domain, security); Parameters : The setcookie () function requires six arguments in general which are:
Parameters: Name: It is used to set the name of the cookie. Value: It is used to set the value of the cookie. Expire: It is used to set the expiry timestamp of the cookie after which the cookie can’t be accessed. Path: It is used to specify the path on the server for which the cookie will be available. Domain: It is used to specify the domain for which the cookie is available. Security: It is used to indicate that the cookie should be sent only if a secure HTTPS connection exists.
Cont. The following example creates a cookie named "user" with the value "John Doe". The cookie will expire after 30 days (86400 * 30). The "/" means that the cookie is available in entire website (otherwise, select the directory you prefer). We then retrieve the value of the cookie "user" (using the global variable $_COOKIE). We also use the isset () function to find out if the cookie is set:
Operations that can be performed on Cookies in PHP:
Creating Cookies : Creating a cookie named Auction_Item and assigning the value Luxury Car to it. The cookie will expire after 2 days(2 days * 24 hours * 60 mins * 60 seconds).
Example <? php $ cookie_name = "user"; $ cookie_value = "John Doe"; setcookie ($ cookie_name , $ cookie_value , time() + (86400 * 30), "/"); // 30 day ?> <html> <body> <? php if(! isset ($_COOKIE[$ cookie_name ])) { echo "Cookie named '" . $ cookie_name . "' is not set!"; } else { echo "Cookie '" . $ cookie_name . "' is set!< br >"; echo "Value is: " . $_COOKIE[$ cookie_name ]; } ?> </body> </html>
Checking Whether a Cookie Is Set Or Not It is always advisable to check whether a cookie is set or not before accessing its value. Therefore to check whether a cookie is set or not, the PHP isset () function is used. To check whether a cookie “ Auction_Item ” is set or not, the isset () function is executed as follows:
Example <!DOCTYPE html> <? php setcookie (" Auction_Item ", "Luxury Car", time() + 2 * 24 * 60 * 60); ?> <html> <body> <? php if ( isset ($_COOKIE[" Auction_Ite "])) { echo "Auction Item is a " . $_COOKIE[" Auction_Item "]; } else { echo "No items for auction."; } ?> </ body> </html>
Delete a Cookie To delete a cookie, use the setcookie () function with an expiration date in the past : <? php // set the expiration date to one hour ago setcookie ("user", "", time() - 3600); ?> <html> <body > <? php echo "Cookie 'user' is deleted."; ?> </body> </html>
What is a PHP Session? When you work with an application, you open it, do some changes, and then you close it. 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.
Cont . Session variables solve this problem by storing user information to be used across multiple pages. 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. Session variables are set with the PHP global variable: $_SESSION.
<? php // Start the session session_start (); ?> <!DOCTYPE html> <html> <body> <? php // Set session variables $_SESSION[" favcolor "] = "green"; $_SESSION[" favanimal "] = "cat"; echo "Session variables are set."; ?> </body> </html>
Get PHP Session Variable Values <? 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 " . $_SESSION[" favanimal "] . "."; ?> </body> </html>
Cont. Another way to show all the session variable values for a user session is to run the following code: <? php session_start (); ?> <!DOCTYPE html> <html> <body> <? php print_r ($_SESSION); ?> </body> </html>
Destroy a PHP Session To remove all global session variables and destroy the session, use session_unset () and session_destroy (): <? php session_start (); ?> <!DOCTYPE html> <html> <body> <? php // remove all session variables session_unset (); // destroy the session session_destroy (); ?> </body> </html>
END
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