Auto refresh when new user comes online

Question

I have a table in the database which includes all active users. I then have a user list which needs refreshing to see who is the latest users online. Whats the best way to tackle this? The user list is always just who is in the active_users table. Thanks for reading.

Answer 1

AJAX

You could use an AJAX request to pull regularly the list of active users and display them on your website.

You may want to cache that list for a little while on your server in case you have a lot of users requesting it constantly.

Or, if the list is long, or if you decide to pull a lot of HTML markup with the list, you could also regularly poll your server to check whether there are updates to the (cached...) list since the last time the client updated the list. The reply will be a simple true or false, and the client will only have to request the new list when it has changed.

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Meta refresh tag

You could also use the meta refresh tag, either to update the entire page, or an iframe if you don't mind iframes.

Refresh after one minute:

<meta http-equiv="refresh" content="60" />

Or with an url:

<meta http-equiv="refresh" content="60;url=http://site.com/list.php?counter=1" />

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Manual update

Finally, you may just add a button or a simply a link at the end of the list, and the user could decide for herself whether to reload or not.

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Other considerations

As JoeGeeky pointed out in the comments, for performance and bandwidth reasons, you may want to implement a counter which limits the maximum number of times the user list is loaded. This is valid for Ajax and Meta refresh tags. In javascript you could simply have a variable incrementing every time you load the list, and in case of the meta refresh tag you could add the counter in the url as a get variable.

Also those three approaches do not exclude each other but should be combined: Use Ajax for the folks with javascript activated, a meta refresh iframe in a noscript tag as a fallback for the ones with javascript disabled (as mentioned by stagas), and a button or link for manual update once the maximum list reload count has been reached.

Answer 2

If your userlist is short, for example, you are just displaying the latest five users, I would go with a simple polling with Ajax to a PHP script that returns that data.

You can adjust the polling to whatever your needs are,

$(document).ready(function () {
    function refreshUserlist () {
        $.ajax({
            url: "user_list.php",
            success: function (data) {
                // code to refresh your website with the info out of data

                setTimeout(refreshUserlist, 5000);
            }
        });
    }

    refreshUserlist();
});

Answer 3

Simplest way I can think of is that you can make a simple php page that lists the data, and use jQuery .load() function to load that php's html response into a div

$("#divid").load("active-users.php");

Answer 4

Make a php script to retrieve the list of active_users and return a <ul> list. Then use jQuery and setInterval() to fetch that list with $.ajax() and replace the list every 1-2 minutes or so with $('#active_user_list').html(new_list_data). Here's what it might look like (untested) :

setInterval(function() {
   $.ajax({ url: 'script_to_fetch_active_users_list.php', success: function(new_list_data) {
      $('#active_user_list').html(new_list_data);
   } });
}, 1000*120);

The php script is up to you...