This is a pretty long question in words, but it all adds up to one function.
For some time, I have tried figuring out how to increment a variable, save it and then display it. Only problem is I figured out that to save the variable and allow all users on the website to see the same updated variable, it has to be saved server side, so now I have a big question as I have tried to figure out one thing, and now has to do it another way.
To store a variable server side, is it enough to save the variable in a .php script because if so, I think what I am looking for is a way to have a variable in a .php script, then when a specific function is called I want to increment this variable by one, and then last I want to save this variable server side, to always be able to have the exact same variable on all users screens. The .php script is called by a form from the html script, so there is no problem there, the problem is as mentioned above, how to make a variable in .php script, increment that variable when a function is called, save that variable and then pass it back to the html page to display.
At first one may think of a Session variable, But as you pointed out it should be shared among all users, you need to save it into a database, file or use a cache server.
Are you using a database? You can create a single table containing a key and value columns. Then you keep the row with the specified key up-to-date with the variable value you want to keep track of.
If you don't have access to a database server, you can serialize the variable or simply store it as a text file and read from it. Only problem here is concurrency, if you have too many users at the same time, you won't be able to update it at once.
Cache server is a bit more complicated to explain, but you could look for further documentation about that.
Good luck!
Related
It is possible to keep a variable after a refresh?
Sessions don't work, because it's on the server side.
I mean, I have a class with an array var.
I would like to add a string to the array in another php site (includes "CLASS"), but when I refresh the site, the array is empty.
Everything is run through again, so it gets lost.
Perhaps you want to store it in $_SESSION? Sessions work on the server side.
You could also write data to a file and read it every time.
I'm working on a company intranet system and have a function to load a form via include while passing an url encoded array in GET format
$draftcook = urlencode(serialize($draft));
include(FORM_PATH .'newrangesubtypeform.php?draft=yes&type='.$value.'&draftcook='.$draftcook);
Unfortunately my array has gotten too long to be able to be passed via a url, I have tried many other alternatives, including setting the array into a session variable and then pulling it through in the included form but that for some reason is unable to see the session variable.
Could someone please suggest a work around for this situation, the array itself is likely to have upward of 1000 fields in it by the time the whole page is completed if that effects the solution.
Thanks
You can write into db or file a threat (id, draftcook) and pass the PK of the threat vía URL and then get the draftcook
Included code runs in the same scope as wherever you called include. I'm not even sure why you're passing this stuff info the new file; any variable that exists can be used in the include.
So you can access $draft as a regular variable already.
I started writing a web application that stores certain user information in the $_SESSION variable. Usual stuff - user_id, username etc.
I then started using the variables to store certain navigation information. For instance, $_SESSION['organisation_id'] so that wherever the user is in the application, I can easily add 'organisation_id' to any table without having to parse 'organisation_id' across every page request (eg. index.php?organisation_id=456&var2=6 or anotherpage.php?organisation_id=456& etc)
All hunky dory until a user opens a new tab and starts navigating to another organisation so hence creating a new $_SESSION['organisation_id'] value and creating an epic fail on the original tab.
The only solution I can think of is to go back to putting organisation_id into every form and navigation element within the application but yeesh, I'm thinking there must be a more elegant solution.
Normally, I find everything I need on StackOverflow but the answer to this question still eludes me!
"The only solution i can think of is to go back to putting organisation_id into every form and navigation element within the application but yeesh, i'm thinking there must be a more elegant solution."
No there isn't.
Maybe you can check if $_SESSION['organisation_id'] exist, and if so you can write new variable in session with different name, and so one.
Currently there is no way to solve the problem. But to avoid a similar task in the future, I would suggest split up all your files into different includes.
So even if you have to add a couple of variables to the entire site, you could modify 1 file and get it done than doing the whole thing again.
I think this is a logic problem. The session represents a state for the user. This is because HTTP is a stateless protocol in it's essence (it don't know who is who, just undersdants requests and responses).
So the organization_id is a state. If a user can login to just one organization, you just store this in the session var like you did and use it. If the user logs out and in again with another organization_id, it makes sense that only the last one remain available.
If your application has to support multiple organization_id's, you should reflect that logic in your session handling, saving an array of organization ids for instance (instead of just one). But then you have to change your application to allow the user to navigate from organization to organization, etc. There's no point in letting the user be in two organizations at once if the screen just shows one of them.
you can store the value into session during onblur of that username, etc and you can get it before you clicking the next tab
(i.e) using Jquery/Javascript u can get that value of username, etc while onblur and store it in session.
You can resolve this by simply moving the data you currently put into the $_SESSION array into a sub-array within $_SESSION, so that you can store multiple sets of data at once in the session.
It would end up looking a bit like this:
$_SESSION[organisations] = array(
'456' => array('organisationID'=>456, 'otherdata'=>'blah'),
'678' => array('organisationID'=>678, 'otherdata'=>'blah'),
...etc...
);
This will allow you to keep the data for multiple orgs in the session data at once, so you don't have to load all the data every time.
But yes, you will need to send the relevant organisationID with every request, so that your code knows which element of the session data to work with. You can't really work around that. Every request will need tell PHP which orgID to work with.
The down-sides here are that by storing all that data in the session, you're using a lot more memory for your session data, so if there's a chance that the user will browse a lot of organisations during a session, I would advise limiting the size of $_SESSION by dropping data that hasn't been used for a while.
The other down-side is that if this is a multi-user system, storing the data in session means that it will be unaware of any updates made by other users. If you were to load the data fresh from the database on every request, yes it would create more work for the DB, but it would ensure that the data given to the user was always up-to-date.
Normally I try to format my question as a basic question and then explain my situation, but the solution I'm looking for might be the wrong one altogether, so here's the problem:
I'm building a catalog application for an auction website that has the ability to save individual lots. So far this has worked great by simply creating a cookie with a comma-separated list of IDs for those lots, via something like this:
$_COOKIE["MyLots_$AuctionId"] = implode(",",$arrayOfIds);
The problem I'm now hitting is that when I go to print the lots, I'm using wkhtmltopdf through the command-line to request the url of the printout I want, like this:
exec("wkhtmltopdf '$urlofmylots' filename.pdf");
The problem is that I can't pass a cookie to this call, because Apache sees an internal request, not the request of the user. I tried putting it in the get string, but once I have more than a pre-set limit for GET parameters, that value disappears from the $_GET array on the target url. I can't seem to find a way to send POST data between them. My next possible ideas are the following:
Maybe just pass the sessionID to the url, and see if there's a way that I can use PHP to dig through the cookies for that session and pull the right cookie, but that sounds like it'd be risky security-wise for a PHP server to allow (letting one session be aware of another). Example:
exec("wkhtmltopdf '$urlofmylots?sessionId=$sessionIdFromThisRequest' filename.pdf");
Possibly set a session variable and then pass that session Id, and see if I can use PHP to wade through that information instead (rather than using the cookie).
Would I be able to just create an array and somehow have that other script be aware of it, possibly by including it? That doesn't really solve the problem of wkhtmltopdf expecting a web-facing address as its first parameter.
(not really an idea, but some reasoning) In other instances of using this, I've just passed an ID to the script that generates the markup for wkhtmltopdf to parse, and the script uses that ID to get data from the database. I don't want to store this data in a file or the database for the simple purpose of transferring data from the caller to the callee in this case. Cookies and sessions seem cleaner since apache/php handle memory allocation for these sessions.
The ultimate problem here is that I'm trying to get my second script (referenced here by $urlofmylots) to be aware of data available to the calling script but it's being executed as if it were an external web request, not two php scripts being called from the web root.
Can anyone offer some insight here?
You might consider rendering whatever the output of $urlofmylots?lots=$lots_to_print would be to a temporary file and running wkhtmltopdf against that file.
Using PHP.. I have a small app that I built that currently uses a querystring to navigate and grab data from a database. The key in the database is also in the string and that is not acceptable anymore. I need to change it. I would like to hide the db key and use a session in place of it but I'm not sure how to do that. In fact, there are also other variables in the query string that I would like to use sessions for if at all possible.
page.php?var1&var2&id=1
This is what my string looks like. I am looping through the results in the database and have given each row the id so that when the user clicks the row they want, but I'm not sure how I could do this with a session.
Does anyone have any ideas?
Thanks
EDIT:
I'm developing an email type system where senders and recipients are getting and sending mail. Each piece of mail that is stored on the server will have its own unique key. Currently, I am using that number to retreive the message but the problem is that I don't want people to change the number and read other people's mail. I can probably use a GUID for this or even some sort of hash but I really hate long query strings. I was just thinking it would be so much cleaner if there was a way to "hide" the id all together.
UPDATED (Again ... Yeah, I know.)
Allowing access to a particular set of data through a $_GET parameter is much more accessible to any user that happens to be using the application.
UPDATED
For storing a private record key, you are probably going to want to use post data, and if you really want it to look like a link, you can always use CSS for that part.
Honestly, the best way to stop people from reading other people's mail is by having a relationship table that says only X person is able to access Y email (by id). That or have a field that says who is the 'owner' of the email.
The fact is that users can still get access to POST parameters, and can easily forge their own POST parameters. This means that anyone could realistically access anyone else's email if they knew the naming scheme.
In an ideal system, there would be a Sender, and a Recipient (The Recipient could be comma separated values). Only the people that are on one of those columns should be allowed to access the email.
How To Use Sessions (From Earlier)
First start off with calling session_start(), and then after that check for variables from previous scripts. If they aren't present, generate them. If they are, grab them and use them.
session_start();
if(!isset($_SESSION['db_key']))
{
$_SESSION['db_key'] = // generate your database key
}
else
{
$db_key = $_SESSION['db_key'];
}
Sessions are stored in the $_SESSION array. Whenever you want to use $_SESSION, you need to call session_start() FIRST and then you can assign or grab anything you like from it.
When you want to destroy the data, call session_destroy();
Also check out php.net's section on Sessions
Your question isn't too clear to me, but I understand it like this:
You need some variables to decide what is being displayed on the page. These variables are being passed in the URL. So far so good, perfectly normal. Now you want to hide these variables and save them in the session?
Consider this: Right now, every page has a unique URL.
http://mysite.com/page?var1=x&var2=y
displays a unique page. Whenever you visit the above URL, you'll get the same page.
What you're asking for, if I understand correctly, is to use one URL like
http://mysite.com/page
without variables, yet still get different pages?
That's certainly possible, but that means you'll need to keep track of what the user is doing on the server. I.e. "user clicked on 'Next Page', the last time I saw him he was on page X, so he should now be on page Y, so when he's requesting the site the next time, I'll show him page Y."
That's a lot of work to do, and things can get awkward quickly if the user starts to use the back button. I don't think this is a good idea.
If you need to take sensitive information out of the URL, obfuscate them somehow (hashes) or use alternative values that don't have any meaning by themselves.
It completely depends on your application of course, if the user is accumulating data over several pages, Sessions are the way to go obviously. Can you be a bit more descriptive on what your app is doing?
Edit:
but the problem is that I don't want people to change the number and read other people's mail
If your primary concern is security, that's the wrong way to do it anyway. Security through obscurity is not gonna work. You need to explicitly check if a user is allowed to see a certain piece of info before displaying it to him, not just relying on him not guessing the right id.
There are some examples on how to use $_SESSION on php.
Registering a variable with $_SESSION
The issue with using sessions for using it in place of S$_GET or $_POST is that you need some way to read the user's input so that you can store it in the session, and you need a way to trigger a page refresh. Traditional means is via hyperlinks, which defaults to GET (unless you use Javascript) or forms, which defaults to POST.
Maybe ajax will help you here. Once the user has enter info into a form or a checkbox, use JS to send a request to insert the info to the PHP and send info back, whether it is to refresh the page or to fill a with content.
Hope this helps