Why does avatar disappear upon revisiting page? - php

Question

When a user submits a picture, the file is moved to a generated folder (for security purposes) with its file pathway recorded on the database. The picture displays correctly when the user stays on the page, but when the user exits from the page and revisits it, the picture they had previously uploaded fails to display (nothing displays at all). I seem to be unable to evoke the image from its location through its session variable and would like insight on this, thanks.
What I've tried:
echoing the avatar session variable -> image doesn't display at all
echoing the location of the image -> image displays when the user does not leave page after submitting. When the user leaves and
revisits the page, the image does not display. In its place, a
outline of where the image is suppose to register shows.
A lot of small tweaks (for instance, setting avatar session variable to location, and so on).
Here is my code:
$fln = $_FILES['avatar']['name'];
if(isset($fln) && tmp_name !== "") {
$tmp_name = $_FILES['avatar']['tmp_name'];
$fls = $_FILES['avatar']['size'];
$chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
$rdn = substr(str_shuffle($chars), 0, 15);
//size checker
if($fls > 6500000) {
echo "Image must be less than 6.5 MB...";
}
else {
mkdir("user_data/user_avatars/$rdn/");
$location = "user_data/user_avatars/$rdn/$fln";
move_uploaded_file( $tmp_name, $location);
$imageCD = "UPDATE users SET avatar=? WHERE email=? LIMIT 1";
$imageST = $con->prepare($imageCD);
$imageST->bind_param('ss', $location, $_SESSION["email_login"]);
$imageST->execute();
$_SESSION["avatar"] = $location;
}
}
else {
$location = "/img/default_pic.jpg";
}
Here is where the image is suppose to display:
<img src="<?php echo $_SESSION["avatar"]; ?>" class="profilePic" id="profilePic" />

Answer 1

The session variable will only be active as long as the user doesn't close the browser.
So if you're trying to echo $_SESSION["avatar"] it will work when the user just uploaded the avatar and surfs around on your page. When they leave and come back later, the session has been cleared. Furthermore, the session is only between the current user and the webserver and the avatar will only be displayed for the user itself, and not anyone else on your site!
It will therefore not be the ideal solution to load the image from session!
Every time a user visits your page you need to load their information from your database (including the avatar path) and display it directly from there.