Save div to a cookie

Question

I’m starting to mess with cookies, so I don’t know much. I was hoping he’d save a certain <div> but I don’t know how to do it.

Like I’m doing:

check if that cookie exists:

$nomecoook = $_GET['cont'];
if(isset($_COOKIE[$nomecoook])){

}else{
    $sql="SELECT img FROM fotos WHERE tkm='$tkm'";
    $exe= mysqli_query($link,$sql);
    $numrow=mysqli_num_rows($exe);
    setcookie($nomecoook,'1',(time() + (24 * 3600)));
}

the div I want to save:

<div class="carousel-inner">
     <?php
        $i=0;
        while($row=MYSQLI_FETCH_ARRAY($exe)){
           $i++;
           $img=$row['img'];
           if($i==1){
      ?>
           <div class="item active">
               <img src="../_img/<?php echo e($img) ?>" alt="First Slide">
           </div>
      <?php
           }else{
      ?>
           <div class="item">
               <img src="../_img/<?php echo e($img) ?>" alt="Second Slide">
           </div>
      <?php
           }
      }
      ?>
</div>

I want to save the result of this div so I don’t have to make another query in the database. Can anyone help me?

Or if there’s a way to save the entire page to that cookie.

Answer 1

Your intention seems to me to use a cache, to avoid database queries.

You need to think about whether this is feasible first. Is the data you are searching constantly changed? Or never?

If the answer is "never," then we can move on to the next paragraph.

Did you know that Cookie has a size limit? ever thought that "saving the whole page" or a "div" might be impossible or unviable?

Another thing: You know that the cookie, unlike the session, could have the values modified directly in the browser.

If you save the DIV in the Cookie and use it to write the content saved in it by PHP, for example, knew that this can leave your site vulnerable to XSS?

In your case, it seems to me a case for the use of Session or even of using a Header to determine a cache-based response or not.

A small example below to see how the header usage might look Last-Modified (I have used in some cases and works very well):

if (isset($_SERVER['HTTP_IF_MODIFIED_SINCE'])) {

    if (strtotime($_SERVER['HTTP_IF_MODIFIED_SINCE']) < time()) {
        header('HTTP/1.1 304 Not Modified');
        // não executará a consulta, mas dará a última resposta, que foi salva no cache do navegador
        exit;
    }
}



header(sprintf("Last-Modified: %s", (new DateTime())->format(DateTime::COOKIE)));

// faça a sua consulta aqui

The above code is very simple and you can adapt it very well to your need. I do not intend to give an answer in order to make for you, but I want you to understand what, for your case, cookie does not solve.

Important information: Some browsers ignore the Last-Modified when used in localhost. So for testing, maybe you might have difficulties if you use it. I think I solved this by creating a fictional domain in the archive hosts.

Here are some answers about cache, session and the like:

• Save or not cache browser?

• https://stackoverflow.com/questions/1971721/how-to-use-http-cache-headers-with-php

• https://stackoverflow.com/questions/49547/how-to-control-web-page-caching-across-all-browsers?rq=1