Link change SESSION var - session

Question

I have a listing page for an e-commerce website with various items (item_list.php). This page is generated with a PHP loop and displays each item inside a <li> element. Every item is a link to the same page, called item_details.php .
When clicking on the link i want to run a script that changes a SESSION var to a certain $id (which will be excracted from the <li> itself with .innerHTML function) and then allowing the browser to move into the next page (item_details).
This is needed so i can display the proper information about each item.
I think this is possible with Ajax but I would prefer a solution that uses JS and PHP only.
(P.S.This is for a University project and im still a PHP newbie, i tried searching for an answer for a good while but couldn't find a solution)

Answer 1

No JS or other client-side code can set session values, so you need either an ajax call to php, or some workaround. This is not a complete answer, but something to get you thinking and hopefully going on the project again.
The obvious answer is just include it in the link and then get it in PHP from the $_GET -array, and filter it properly.
item title
If, however, there is some reason this is not a question with an obvious answer:
1.) Closest what you're after can be achieved with a callback and an ajax call. The idea is to have the actual link with a click function, returning false so the link doesn't fire at once, which also calls an ajax post request which finally will use document.location to redirect your browser.
I strongly advice against this, as this will prevent ctrl-clicks causing a flawed user experience.
Check out some code an examples here, which you could modify. You will also need an ajax.php file which will actually set the session value. https://developers.google.com/analytics/devguides/collection/analyticsjs/enhanced-ecommerce#product-click
2.) Now, a perhaps slightly better approach, if you truly need to do this client-side could be to use an click handler which instead of performing an ajax call or setting session directly, would be to use jQuery to set a cookie and then access this data on the item_list.php -page.
See more information and instructions here: https://www.electrictoolbox.com/jquery-cookies/
<script>
$('product_li a).click(function(){
$.cookie("li_click_data", $(this).parent().innerhtml());
return true;
});
</script>
......
<li class="product_li">your product title</li>
And in your target php file you check for the cookie. Remember, that this cookie can be set to anything, so never ever trust user data. Test and filter it in order to make sure your code is not compromised. I don't know what you want to do with this data.
$_COOKIE['li_click_data'];
3.) Finally, as the best approach, you should look at your current code, and see if there is something you can re-engineer. Here's a quick example.
You could do the following in php to save an array of the values in the session on each page load, and then get that value provided you have some kind of id or other usable identifier for your items:
// for list_items.php
foreach($item as $i) {
// Do what you normally do, but also set an array in the session.
// Presuming you have an id or some other means (here as item_id), to identify
// an item, then you can also access this array on the item_details -page.
$_SESSION['mystic_item_data_array'][$i['item_id]] = $i['thedata'];
}
// For item_details.php
$item_id = // whatever means you use to identify items, get that id.
$data_you_need = $_SESSION['mystic_item_data_array'][$item_id];
Finally.
All above ways are usable for small data like previous page, filters, keys and similar.
Basically, 1 and 2 (client-side) should only be used, if the data is actually generated client-side. If you have it in PHP already, then process it in php as well.
If your intention is to store actual html, then just regenerate that again on the other page and use one of the above ways to store the small data in case you need that.
I hope this gets you going and at least thinking of how to solve your project. Good luck!