I'm designing a simple board game in jquery/php. The state of the board is currently stored server-side in a php session variable as an array. Each turn is executed as an ajax call to php, which executes logic to update this array, and returns the array to jquery to render as html. I'm achieving persistence of board state with php session variables...but I don't think this is good practise. I can't even play it in multiple tabs, because the browser treats both tabs as part of the same session. I would like to find a solution other than store board state in a database...but if this is the only reasonable solution please let me know :). Thanks!
How about a javascript library like Lawnchair to store the data on the client side?
by default, lawnchair will persist using dom storage but if other adapters are available and dom
storage isn't supported by the currently executing javascript runtime. lawnchair will attempt each
successive adapter until it finds one that works. easy.
It Dom storage spans across tabs as well.
via Dive.Into.Javascript
The data stored in the local storage area does not expire and spans accross different tabs and/or windows
you can store the data in client side using javascript. Either place in hidden fields or use mechanisms like jquery data like this:
$('body').data('player1-pos-x', x);
$('body').data('player1-pos-y', y);
The issue with it is when you refresh the browser, everything is lost.
Another way is store data both in sever side and client side. you can store a game-id, session-id pair to group games under the same session. When browser refresh, you'll have all the game that session relates to and make a decision with the data.
Related
I would imagine it would be done with a cookie or session, but what is the best way to remember an accordion menu's state if a user opens an item and leaves? How can I have "open" items in that state when the user comes back to the site?
I've just upgraded my custom CMS with a new interface, and the new menu needs something like this or usability will suffer greatly.
I don't need specifics, just how you would normally do it.
Thanks!
http://www.shopdev.co.uk/blog/cookies-with-jquery-designing-collapsible-layouts/
this helped me out, hopefully it does for you as well.
I think you would need to save it to a database or use local storage (which isn't supported by all browsers). Cookies would work, but they can be deleted by the user (so can local storage). Sessions wouldn't work because once the user closes their browser, they lose their sessions.
Saving to a database or flat file is the most bulletproof way to do it.
Like most things, it depends.
If this is something that will make a server side request, then storing it in the session global would be completely acceptable.
If it's not, then you would need to find some other method of storing it client side. These would include things like storing it in javascript (only available the page's life), a cookie (like you mentioned) or like Bryan Downing mentioned with local storage. Local storage doesn't have good browser support yet.
Do you want it to be remembered regardless of the computer they log in from? If you do then set a simple value in a table associated to that user as to which item is open so it can be open the next time they return.
I use the jquery UI accordion and it's easy to update a field to which option was last selected so the next time the user comes back I can have that remembered for them. I've done this with a simple ajax call to request the value from the DB and return it to my javascript as a variable that's then used to set the opened accordion section.
If you're not worried about remembering across different devices then a simple cookie should do the trick, just updated the cookie each time a selection is made.
I'm using JS Objects to sort and filter a table but I need to store the original table data in case the user wants to return to it. I'm just wondering if there's an easy way to pass the object's data to a PHP session var, via AJAX, and retain stuff like the key/value relationships without doing a lot of heavy lifting.
Build a JSON-string of the object and store this string.
JSON.stringify
It's not possible.
On the client side, the session is identified by a cookie. The session ID is all you've got.
On the server, the session data is stored in a binary file, one file per session (typical scenario).
So you can't touch the contents from the session from the browser without help from the server.
And second: it's not "light". In an app I've been working on, modern computer and virtually no load yet, loading the session seem to be taking around 250ms, 10 times longer than the response time for the whole page when starting from scratch.
In summary:
you cannot touch session variables without writing a script on the server that handles the data
It's not "light".
OK Ive written this neat javascript 'thing' using jquery and ajax. Its all based on the idea that a div has an attribute that lets you write inside the div. (contenteditable=true). I thought it would be cool to make a chatroom type thing out of it, and holy cow its doing some cool stuff(*), but I have an issue.
Using ajax I post to a php page that takes the posted data (x,y, text, id) and stuffs it into a JSON-like object. Without writing to a database (overkill I think), how can I make this data persist? See the problem? : The variables in a php page are essentially vapor after the page has ran, so my javascript ajax call to retrieveNewJSON() would find nothing.
*using jquery effects and setting colors I have variably placed text that scrolls and evaporates, matrix style, for example. Also, a cursor is placed in the div where the user clicks.
You have to store the data somewhere. If you don't want to use a full blown database you can store them in flat files (ie: txt) and use PHP's file functions to handle the files.
Of course this is not very scalable, and I'd strongly recommend using a database if you are going to be using this a lot.
You could use cookies (client-side) or session variables (server-side), or you could write to a file for longer-term storage.
You could use a the $_SESSION variable to persist data.
// Call at start of PHP script
session_start()
//....
// Store object
$_SESSION['obj'] = json_encode(obj);
in your pull script:
// Call at start of PHP script
session_start()
// Retrieve object
echo $_SESSION['obj'];
Note that when using sessions you have to make sure that you call session_start() at the top of every php script that uses the session.
I would not recommend trying to store this in a file unless you are supporting a very low number of users and have taken proper data sanitation steps to physically write files to the server. If you need this to persist past the length of a session you should be using a database.
It is worth noting that you can't update a users session without some other form of centralized storage. Unless you have some sort of long-polling / comet type setup you will have to have some sort of central storage place. Something I would take a look at would be memcache.
If you want to avoid using a database engine (which would have a lot of overhead for a multiple-read, multiple-write app like a chat room anyway), you might look at a simple object store like memcache, couch, or mongo. Files are also a valid option, provided you store them outside of the Web root with proper permissions. Bottom line is, you'll have to use some sort of storage engine on the back end in order to make the data shareable across multiple user sessions.
If this is simply a tech demo or a proof of concept, I wouldn't worry too much about overhead right away.
I'm just playing around with some PHP and was wondering what happens when an object from a class is created within another PHP script?
I assume once its created and been processed their is no way of then going back and 'playing' around with it from another script?
The idea is i'm trying to create a kind of deck of cards using a card class, each card has specific data that is added to each individual object to make it unique, suit, value etc. Once its created i need to be able to go back to specific cards to use them. In java i'd have an arraylist of card objects, i'm not sure how to approach the same area in PHP.
Thanks.
There is no problem passing objects around inside a php script, your problem is that php is that the webserver calling the script is essentially "stateless". i.e. every time someone posts the url from a browser a complete fresh copy of the php program is fired up.
To save data between times there are several options:-
One is to use $_SESSION variables which are associated with a user session but $_SESSION itself is an array so it gets really clumsy holding complex structures here, also , it sounds like you want to share the deck between users.
You could serialise your object and store it in a file -- which is OK as long as its not updated very often -- but if its updated by every user they will start overwriting each others changes.
Much better is to store the deck in a database (SQLITE is usually built into php) so that several users can share and update in a controlled manner.
Another good option would be to use one of the popular data caches such as "memcached" which will cache the data between calls to the script.
To reuse an object between page calls seems to be your issue. Maybe you can serialize the object and store it in database and pick it up back?? Check php.net/serialize Let know how it goes.
What you could do to keep the objects available to you is to serialize the objects and store them in a database table. If you link a game ID or something similar to the cards then you can retrieve them later using this game ID.
I don't know if the cardgame you are writing is realtime, using a database might be too much overhead. Another possibility is to use an existing caching solution, like for example Memcache.
So you want to create a serverside coded cardsgame? Good luck!
It is possible to do this, tho I think a script like a javascript you are talking about is much more suitable.
You could make a function that initialises a deck of cards and work with indexes etc. Save your things in cookies / sessions and work with postbacks. It's gonna be a hell of a job tho in my opinion compared to jscript.
Tho when you think about it, you could use ajax to make this game feel better for the user :).
Php scripts are not like Java server apps.
Where your Java server will run for a long time, your php script will just be a one time thing.
Instead of this kind of process : user make a request to Java-run server, server receive the request in one of it's infinite loops, server process it, server send the response, server wait for new request; you have this kind of thing : a webserver (Apache, Nginx, whatever other webserver) receive the user's request, understand it needs to be interpreted by php, starts a php child, this child do what's in the script, send its answer, dies, the server wait for new requests.
So, when a php script ends, nothing (in good case) is left from it.
But, a php script can use persistent storage on the server so another request can read from it. That's why you have files, databases and even shared memories functions.
If the games state is for one user only, you can use sessions (usually files) to store your deck object. If it's meant to be used by multiple players, you should store it after serialization in a database.
I have been poking around in PHP for OOP and I noticed something... Objects are re-instantiated each time the page is refreshed. The problem is that I want the object to keep certain information in class variables for the whole time that someone is on a website.
Is there some sort of way to keep an
object alive the whole time that
someone is surfing on the website?
What alternatives are there to my
problem?
It would be really helpful to have example too!
You can use Sessions to keep data associated to one user between different pages (quoting) :
Session support in PHP consists of a
way to preserve certain data across
subsequent accesses.
See the Session Handling section of the manual, for more informations about sessions.
PHP isn't stateful. Every page load is a one time event. You can persist data with sessions, or by storing information in a database.
A php script has to exit before apache can serve the page, so if you really want to do that, one thing you can do is serialize and store all the objects that you want to persist and use session cookies to keep track of the users
PHP isn't statefull every request is a new process on the server
Your best bet is to use session data and hand the session data to the objects when you instantiate them. Have the contructors pull the data they need out of the session, and you'll essentially have the state fullness you need.
you can acess sesion using
$_SESSION['stuff'] = $data;
then you can use your objects like
$x = new DataStore($_SESSION['stuff']);
if theres data in the session the object will populate itself from that data. Otherwise it will default to its standard init.
Even when approaches like serializing objects and then deserializing them is useful, you have to make sure you understand first why your objects "disappear".
HTTP, the protocol used to retrieve pages and other resources from Web servers, is stateless. It basically means one request knows nothing from another request, even when it came from the same user. Think of it this way, when you request your PHP page, the script is run and after it finishes Apache sends out the result to you. When you request the page again, it does the same thing as if it was the very first time you did it. It's stateless.
There are techniques to keep state between requests (make it to not forget your objects) and those involve things like cookies or URL rewriting. But you have to keep in mind the stateless nature of HTTP (and thus your PHP script) when developing Web applications.
SESSIONS are good, i use them to hold object state in some of my PHP programming.
Or a better solution would be to use Flex so you don't have to worry about the stateless HTTP protocol...