I'm trying to save an object in $_SESSION, but the following:
<?php
$user = db->load( $username, $pass ) ;
$_SESSION[ 'user' ] = $user ;
# on subsequent page loads:
$user = $_SESSION[ 'user' ] ; #retrieve the user from session
Unfortunately this doesn't work.
The script tried to execute a method or access a property of an incomplete object. Please ensure that the class definition "User" of the object you are trying to operate on was loaded _before_ unserialize() gets called or provide a __autoload() function to load the class definition
Unless you use serialize():
<?php
$user = db->load( $username, $pass ) ;
$_SESSION[ 'user' ] = serialize( $user ) ;
# on subsequent page loads:
$user = unserialize( $_SESSION[ 'user' ] ) ; #retrieve the user from session
I'm assuming a serialize is required because Session info is saved out to disk. But shouldn't PHP be smart enough to serialize stuff on its own?
And with the use of serialize/_unserialize_, is this going to work now reliably? Or do I need a __serialize() method in my PHP class?
You would need the __serialize() in your class if your object needs to perform some action before being serialized. For instance if it had a reference to an open file and that file needed to be properly closed before serializing.
Could you maybe use var_export? I only just learned about it today, so maybe it's not really that relevant.
As far as the php compiler is concerned all you are doing is writing an object (serialised) to an Array its a different process that ensures $_SESSION is available on the next page. Serialisation is nothing to do with being written to disk more to do with memory as the memory allocated to various methods on your object will not be available on the next page. Serialisation is how PHP holds onto objects accross pages, and you have to do it yourself.
Better Use
json_encode() json_decode()
Probably the best approach this days is to implement Serializable interface with your class.
Related
I am passing an array of WP objects (ie, WP_User) from Wordpress site to a popup window using $_SESSION variable.
When popup is open, I var_dump($_SESSION['variable']['WP_Users']) and everything looks good.
However, when I am trying to access $_SESSION['variable']['WP_users'][0]->data->parameter, all values are NULL.
Aside from that, error_log says:
"main(): The script tried to execute a method or access a property of an incomplete object. Please ensure that the class definition "WP_User" of the object you are trying to operate on was loaded before unserialize() gets called or provide a __autoload() function to load the class definition in /ABSPATH/popup_template.php line 52"
As I understand, my popup has no definitions of WP classes, such as WP_User etc., therefore I am unable to manipulate WP objects.
Any ideas on how to tackle this? (keep in mind I am not using (un)serialize() at all)
So solution was actually pretty straightforward: I had to do what error_log asked.
In parent window I had to serialize array of Wordpress objects before shoving them into the SESSION var like so:
$_SESSION['variable'] = serialize( $array_of_WP_objects );
To my popup template I had to add definition of WP_User from wp_includes folder, and then unserialize my array back to $array_of_WP_objects like so
require_once( '../../../../wp-includes/class-wp-user.php' );
$array_of_WP_objects = unserialize( $_SESSION['variable'] );
Worked like a charm.
In my PHP code, I create a 'session' object that stores user type, auth etc. (although no password in any form). Then I serialize this object into the $_SESSION var:
$_SESSION['sess_data'] = serialize($session);
when I need to authenticate the user, I do this:
$session = unserialize($_SESSION['sess_data']);
It looks very unsafe to me though. How can I improve it? Would some method as get_class() suffice? Thanks
I am writing a small e-shop application with Symfony 2 and I need some way to store the user's shopping cart in a session. I think using a database is not a good idea.
The application will use entities like Product, Category, ShoppingCart where Product and Category are persisted into the database and users will be choosing products into their ShoppingCart.
I have found NativeSessionStorage class which is supposed to save an entity into a session. But there is no written process of implementation into an application.
Do I use this in the controller or in a separated class ShoppingCart? Could you give me a short example of NativeSessionStorage usage?
EDIT:
The question was not set correctly:
The goal is not to save all product ids into a cookie. The goal is to save only a reference for basket (filled with products) in application memory on server-side and assign proper basket to user. Is this even possible to do this in PHP?
EDIT2:
Is a better solution to use a service?
Don't know if this way is the better way to store your data temporary. You can use this to instantiate a session object :
$session = $this->get("session");
Don't forget the 'use' in your controller :
use Symfony\Component\HttpFoundation\Session;
Then, the session starts automatically when you want to set a variable like :
$session->set("product name","computer");
This is based on the use of the Session class, easy to understand. Commonly definitions :
get(string $name, mixed $default = null)
Returns an attribute.
set(string $name, mixed $value)
Sets an attribute.
has(string $name)
Checks if an attribute is defined.
Also, take a look to the other ways to store your data : Multiple SessionStorage
You can make your entity Serializable and serialize the entity object and save to session and then retrieve in other page using unserialize(). There is one caveat, for an entity that exists in the db Doctrine2 will mark the retrieved/unserialized entity as detached. You have to call $em->merge($entity); in this case.
You can save the whole object into a session with Symfony. Just use (in a controller):
$this->get('session')->set('session_name', $object);
Beware: the object needs to be serializable. Otherwise, PHP crashes when loading the session on the start_session() function.
Just implement the \Serializable interface by adding serialize() and unserialize() method, like this:
public function serialize()
{
return serialize(
[
$this->property1,
$this->property2,
]
);
}
public function unserialize($serialized)
{
$data = unserialize($serialized);
list(
$this->property1,
$this->property2,
) = $data;
}
Source: http://blog.ikvasnica.com/entry/storing-objects-into-a-session-in-symfony (my blogpost on this topic)
The PHP documentation says "You can't use references in session variables as there is no feasible way to restore a reference to another variable."
Does this mean I can't have things like:
session_start();
$user = new User;
$user->name = 'blah';
$_SESSION['user'] = $user;
I have tried to store a simple string and a User object in session, the string always persists between pages to pages, or after page refresh. However the User variable is lost in $_SESSION(becomes empty).
any idea?
Edit:
I have confirmed that session_id is the same in all of these pages/subpages,before & after page refresh.
Edit:
Strangely, after I tried serialize and unserialize approach below, the serialized user object(or string) in session still still disappears!
Edit:
finally I figured out what the bug was, looks like somehow $_SESSION['user'] gets overwritten by some mysterious force, if I use any variable other than 'user', then everything's fine. PHP(at least 5.3 which is the version I'm using) does serialize and unserialize automatically when you put object in the $_SESSION.
session_start();
$user = new User();
$user->name = 'blah'
$_SESSION['myuser'] = $user;
You need to use the magic __sleep and __wakeup methods for PHP 5 Objects.
For example in the following code block:
$obj = new Object();
$_SESSION['obj'] = serialize($obj);
$obj = unserialize($_SESSION['obj']);
__sleep is called by serialize(). A sleep method will return an array of the values from the object that you want to persist.
__wakeup is called by unserialize(). A wakeup method should take the unserialized values and initialize them in them in the object.
Your code example isn't using references as the documentation was referring to. This is what php means by references:
$var =& $GLOBALS["var"];
As to putting objects into the session, PHP can store objects in $_SESSION. See http://example.preinheimer.com/sessobj.php.
What you are seeing is a bug in the order of calls to __sleep and __destruct (__destruct is being called before __sleep) and the session module fails to serialize the object at shutdown. This bug was opened on Sep 1, 2009.
For safe serialization and unserialization encode and decode with base64_encode() and base64_decode() respectively. Below I pass a serialized Object to a session and unserialize it on the other page to regain the variable to an object state.
Page 1
<?php
require $_SERVER['DOCUMENT_ROOT'] .'/classes/RegistrationClass.php';
$registrationData= new RegistrationClass();
$registrationData->setUserRegData();
$reg_serlizer = base64_encode(serialize($registrationData)); //serilize the object to create a string representation
$_SESSION['regSession'] = $reg_serlizer;
?>
Page 2
<?php
session_start();
require $_SERVER['DOCUMENT_ROOT'] .'/classes/RegistrationClass.php';
$reg_unserilizeObj =
unserialize((base64_decode($_SESSION['regSession'])));
$reg_unserilizeObj->firstName;
?>
This article describes issues that may be faced by not doing so.
issuses with php serialization/unserialization
You were right saying you can not store references in sessions variables
assigning an object in PHP 5 and above is doing just that assigning the reference not the obj
That its why you would need to serialize the object (implementing also __sleep in the Class) and assigning the string to a session variable
and deserializing it later (implementing also __wake in the Class) from the session variable later on.
That's the expected behavior. Storing a reference to an object would only work if the memory location for the object didn't change. In a stateless protocol like HTTP, application state is not persisted between requests. The next request may be handled on another thread, process, or another server.
Given the inherent stateless nature of a web application, holding a pointer to a memory location is useless. Therefore the object's state must be broken down into a storage format, saved or transmitted, and then reconstituted when needed. This process is known as Serialization.
You can choose to serialize the entire object into session (which maybe dangerous depending on the depth of your object graph, since your object may hold references to other objects and those would need to be serialized as well), or if the object can be reconstituted by querying the database on the next request you may just stash an ID in the session.
[EDIT]
JPot pointed out that objects are automatically serialized to $_SESSION, so explicit serialization isn't necessary. I'll leave the answer for posterity, but obviously it doesn't help your problem.
I have instantiated a class in my index.php file. But then I use jQuery Ajax to call some PHP files, but they can't use my object that I created in the index.php file.
How can I make it work? Because I don´t want to create new objects, because the one I created holds all the property values I want to use.
Use the session to save the object for the next page load.
// Create a new object
$object = new stdClass();
$object->value = 'something';
$object->other_value = 'something else';
// Start the session
session_start();
// Save the object in the user's session
$_SESSION['object'] = $object;
Then in the next page that loads from AJAX
// Start the session saved from last time
session_start();
// Get the object out
$object = $_SESSION['object'];
// Prints "something"
print $object->value;
By using the PHP sessions you can save data across many pages for a certain user. For example, maybe each user has a shopping cart object that contains a list of items they want to buy. Since you are storing that data in THAT USERS session only - each user can have their own shopping cart object that is saved on each page!
Another option if you dont want to use sessions is to serialize your object and send it through a $_POST value in your AJAX call. Not the most elegant way to do it, but a good alternative if you don't want to use sessions.
See Object Serialization in the documentation for more informations.
mm, you should store in session, $_SESSION["someobj"] = $myobj;, and ensure that when you call the Ajax PHP file this includes the class necessary files which defines the class of $myobj and any contained object in it.
Could you be more specific? I can try.
This is how I create an object then assign it to a session variable:
include(whateverfilethathastheclassorincludeit.php)
$theObject = new TheObjectClass();
//do something with the object or not
$_SESSION['myobject'] = $theObject;
This is how I access the object's members in my Ajax call PHP file:
include(whateverfilethathastheclassorincludeit.php)
$theObject = $_SESSION['myobject'];
//do something with the object
If you don't want to move your object that is in your index.php, have your ajax make a request to index.php but add some extra parameters (post/get) that let your index.php know to process it as an ajax request and not return your normal web page html output.
You have not provided code, but what I guess is that you need to make your instantiated object global for other scripts to see it, example:
$myobject = new myobject();
Now I want to use this object elsewhere, probably under some function or class, or any place where it is not getting recognized, so I will make this global with the global keyword and it will be available there as well:
global $myobject;
Once you have the object, you can put it into the session and then utilize it in the Ajax script file.
As others have suggested, $_SESSION is the standard way to do it, in fact, that was one of the reasons, that sessions where invented to solve. Other options, i.e. serializing the object rely on the client side to hold the object and then return it untampered. Depending on the data in the object, it is not a good solution, as a) the object may include information that should not be available on the client side for security reasons and b) you will have to verify the object after receiving it.
That said, and if you still want to use the object on the client side, then JSON is an option for serializing object data, see JSON functions in PHP.
Based on most of the answers here, referring to storing the object in $_SESSION, is it more efficient to store only the individual properties that need to be accessed in AJAX as opposed to the whole object, or does it not matter?
E.g.
$_SESSION['object'] = $object;
vs
$_SESSION['property1'] = $object->property1;
$_SESSION['property2'] = $object->property2;
I know the OP is asking about accessing the entire object, but I guess my question pertains to if it's just a matter of only accessing certain properties of an object, and not needing to access methods of a class to alter the object once it's in AJAX.