Php session var exists

Php check whether session variable exists or not

Solution 1: Solution 2: use and php function. Solution 3: If you are on php 5.4+, it is cleaner to use session_status(): if sessions are disabled.

Determine if $_SESSION superglobal exists in PHP

use isset() and empty() php function.

if (isset($_SESSION['errors']) && !empty($_SESSION['errors'])) < // . >

if (!isset($_SESSION['id']) || (trim($_SESSION['id']) == '')) < // do stuff >

Detect if PHP session exists

if(session_id() == '' || !isset($_SESSION) || session_status() === PHP_SESSION_NONE) < // session isn't started session_start(); >

If $_SESSION (or $HTTP_SESSION_VARS for PHP 4.0.6 or less) is used, use isset() to check a variable is registered in $_SESSION .

If you are on php 5.4+, it is cleaner to use session_status():

if (session_status() == PHP_SESSION_ACTIVE)

• PHP_SESSION_DISABLED if sessions are disabled.
• PHP_SESSION_NONE if sessions are enabled, but none exists.
• PHP_SESSION_ACTIVE if sessions are enabled, and one exists.

Check if session variable is set by first part of its name

 $example = array(); $example['variable'] = 'abc'; $nextToBeSet = 'var'; $is_exist = false; foreach($example as $k => $v) < if(startsWith($k, $nextToBeSet)) < $is_exist = true; break; >> if($is_exist) echo 'exists'; else echo 'not exists'; 

Demo:
http://3v4l.org/QBj7A

You can simply loop through your $_SESSION and check for existance of «var» with strpos in your sessions key:

 $_SESSION = ['variable' => 1, 'variablesomething' => 2, 'variablesomethingelse' => 3,'else' => 3]; // just for testing, you don't need this replace foreach ($_SESSION as $key => $value) < if (strpos($key, 'var') >-1) < echo 'This key in your Session is set: ' . $key . '
'; > > 

Check if session is set or not, and if not create one?, session_id() returns the string identifying the current session. If a session hasn’t been initialized, it will return an empty string.

Check a sessions variable that may not exist

Edit: Added a new answer based on the latest comments.

I will answer your question in two parts.

Check if a session variable is set or not.

You can check if a variable exists by using empty()

if (empty($_SESSION['is_admin'])) < // do the action if the currently logged in user is not an admin >else < // do the action if an admin user is logged in >

No warning is generated if the variable does not exist. That means empty() is essentially the concise equivalent to !isset($var) || $var == false.

Perform a login check on all protected pages.

It is recommended to add a login check at the top of all pages those are reserved for logged in users.

You can add a login check as follows.

Create a helper function called checkLogin()

Then, wherever you want to restrict unauthorised users accessing the page, include this checkLogin() function.

Be sure you have added this function in a file common to your application

You can try to use if(isset($_SESSION[‘name’]) && $_SESSION[‘name’] )

this code check if variable existe and have some value

This question is solved, although i dont know how to mark it as solved. the key was you have to start the session on every page with session_start();, thanks to invalid bot and Railson luna, either of those will now work!

How to check if a value exists in codeigniter’s session variable, $this->session->username if u want username basically $this->session->key. – Masivuye Cokile. May 14, 2019 at 13:51 · depending on your php

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Check to see if a session has already been started in PHP.

This is a PHP guide on how to check to see if a session already exists.

As you probably already know, session_start is a PHP function which creates a new session.

However, if you call this function more than once, your script will throw an E_NOTICE error.

Although the solution seems pretty straight forward (do not call it more than once), in certain scenarios, you won’t be entirely sure if a session has already been started or not. In some cases, it might be out of your control.

There are two ways to approach this.

Checking to see if a session exists in versions lower than 5.4.

If you are using a PHP version that is lower than 5.4.0, you can do the following.

If you run the code above, you will see that a session is always present.

1. We check to see if the function session_id returns an empty string.
2. If the session_id function returns an empty string, then we can presume that a session does not exist.
3. If this is the case, we can simply start the session by calling the function session_start.

Using the session_status function in PHP 5.4 and above.

In PHP version 5.4.0 and above, we can use the session_status function. As the name suggests, this function returns the status of the current session.

This function can return three different integer values, all of which are available as predefined constants.

• 0 – PHP_SESSION_DISABLED: Sessions are currently disabled.
• 1 – PHP_SESSION_NONE: No session exists.
• 2 – PHP_SESSION_ACTIVE: A session already exists.

If we were to use session_status, our code would look like this:

if(session_status() == PHP_SESSION_NONE)< //session has not started session_start(); >

As you can see, using this function makes your code a little more self-explanatory!

Why not just check if the $_SESSION array is empty?

You can check to see if the $_SESSION array exists and is not empty. However, it is worth noting that $_SESSION can be manually created like so.

In other words, the $_SESSION array can exist even if no session is present.

Another issue is that this array can be empty, even if a session already exists.

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How can I check if a session variable exists without starting a session ? #22

How can I check if a session variable exists without starting a session ? #22

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Not sure if a silly question or not, however here’s my issue:

I am using a plugin that uses sessions for authenticating users ( not WP User ),

following WP guidelines to session_start() in an init hook,
I need to check if a user is authenticated before a start a session, otherwise based on the init hook, session_start() will run for every user, even if they are not authenticated, and im trying to reduce the number of sessions being created.

Do you have any suggestions as to how to access the session array without having to run session_start() for every user ?

The text was updated successfully, but these errors were encountered:

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PHP Session

Summary: in this tutorial, you will learn how to work with PHP sessions to preserve the state of the web application across pages during a session.

Introduction to PHP sessions

The HTTP protocol is stateless. For example, when you visit the product page product.php , the web server responds with the page:

Suppose, you click the add to cart button on the product.php page and navigate to the cart.php page, the web server won’t know that you have added the product to the cart.

To persist the information across the pages, the web server uses sessions. In this example, when you click the add to cart button, the web server will store the product on the server.

When you view the cart.php page, the web server gets the products from the session and displays them on the cart.php page:

• First, the web browser requests for the product.php page.
• Second, the web server responds with the product.php page’s content.
• Third, you click the Add To Cart button on the product.php page. The page will send an HTTP request (either POST or GET) to the web server. The web server validates the product and generates a session id. It also creates a new text file on the server to store the information related to the selected product.
• Fourth, the web server responds to the web browser with the PHPSESSID cookie in the response header. If the web browser allows cookies, it will save the PHPSESSID cookie, which stores the session id passed by the web server.
• Fifth, in the subsequent request, for example, when you view the cart.php page, the web browser passes the PHPSESSID back to the web server. When the web server sees the PHPSESSID cookie, it will resume the session with the session id stored in the cookie.
• Finally, the web server returns the cart page with the products that you selected.

Sessions allow you to store data on the web server associated with a session id. Once you create a session, PHP sends a cookie that contains the session id to the web browser. In the subsequent requests, the web browser sends the session id cookie back to the web server so that PHP can retrieve the data based on the session id.

Creating a new session

To create a new session, you call the session_start() function:

 session_start();Code language: HTML, XML (xml)

When the session_start() runs at the first time, PHP generates a unique session id and passes it to the web browser in the form of a cookie named PHPSESSID .

If a session already exists, PHP checks the PHPSESSID cookie sent by the browser, the session_start() function will resume the existing session instead of creating a new one.

Since PHP sends the PHPSESSID cookie in the header of the HTTP response, you need to call the session_start() function before any statement that outputs the content to the web browser.

Otherwise, you will get a warning message saying that the header cannot be modified because it is already sent. This is a well-know error message in PHP.

Where PHP stores session data

By default, PHP stores session data in temporary files on the web server. You can find the location of the temporary files using directive session.save_path in the PHP configuration file.

The ini_get() function returns the value of the session.save_path directive:

 echo ini_get('session.save_path');Code language: HTML, XML (xml)

Or you can call the session_save_path() function:

 echo session_save_path();Code language: HTML, XML (xml)

Typically, the session data is stored in the /tmp folder of the web server e.g, /xampp/tmp .

Accessing session data

Unlike cookies, you can store any data in the session. To store data in the session, you set the key and value in the $_SESSION superglobal array.

For example, in the index.php file, you store the user string and roles array in the session as follows:

 session_start(); // store scalar value $_SESSION['user'] = 'admin'; // store an array $_SESSION['roles'] = ['administrator', 'approver', 'editor']; ?> html> head> title>PHP Session Demo title> head> body> a href="profile.php">Go to profile page a> body> html>Code language: HTML, XML (xml)

• First, create a new session by calling the session_start() function.
• Second, set the session data with the key user and roles to the ‘admin’ and the array [‘administrator’, ‘approver’, ‘editor] .

The index.php displays a link that navigates to the profile.php page. In the profile.php file, you can access session data as follows:

 session_start() ?>  if (isset($_SESSION['user'])) : ?> p>Welcome = $_SESSION['user'] ?> p>  endif; ?>  if (isset($_SESSION['roles'])) : ?> p>Current roles: p> ul>  foreach ($_SESSION['roles'] as $role): ?> li>= $role ?> li>  endforeach; ?> ul>  endif; ?>Code language: HTML, XML (xml)

• First, resume an existing session created in the index.php file.
• Second, accessing session data using the $_SESSION array.

Deleting the session data

Whenever you close the web browser, PHP automatically deletes the session. Sometimes, you want to explicitly delete a session, e.g., when you click the logout link. In this case, you can use the session_destroy() function:

 session_destroy();Code language: HTML, XML (xml)

This session_destroy() deletes all data associated with the current session. However, it does not unset data in the $_SESSION array and cookie.

To completely destroy the session data, you need to unset the variable in $_SESSION array and remove the PHPSESSID cookie like this:

 session_start(); // remove cookie if(isset($_COOKIE[session_name()]))< setcookie(session_name(),'',time() - 3600, '/'); > // unset data in $_SESSION $_SESSION[] = array(); // destroy the session session_destroy();Code language: HTML, XML (xml)

Notice that we used the session_name() function to get the cookie name instead of using the PHPSESSID . This is because PHP allows you to work with multiple sessions with different names on the same script.

Summary

• Sessions allow you to persist data across pages in a web application.
• Call the session_start() function before any statement that outputs to the web browser for creating a new session or resuming an existing session.
• Use the $_SESSION superglobal array to access the session data.
• Call the session_destroy() function to completely delete session data.

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