How to implement pagination on a custom WP_Query Ajax

Question

I want to paginate my WordPress posts in a custom loop with Ajax, so when I click on load more button posts will appear.

My code:

<?php 
    $postsPerPage = 3;
    $args = array(
        'post_type' => 'post',
        'posts_per_page' => $postsPerPage,
        'cat' => 1
    );
    $loop = new WP_Query($args);

    while ($loop->have_posts()) : $loop->the_post();
?>
<h1><?php the_title(); ?></h1>
<p>
    <?php the_content(); ?>
</p>
<?php
    endwhile; 
    echo '<a href="#">Load More</a>';
    wp_reset_postdata(); 
?>

This code does not paginate. Is there a better way to do this?

Answer 1

The Load More button needs to send a ajax request to the server and the returned data can be added to the existent content using jQuery or plain javascript. Assuming your using jQuery this would starter code.

Custom Ajax Handler (Client-side)

<a href="#">Load More</a>

Change to:

<a id="more_posts" href="#">Load More</a>

Javascript: - Put this at the bottom of the file.

//</script type="text/javascript">

    var ajaxUrl = "<?php echo admin_url('admin-ajax.php')?>";
    var page = 1; // What page we are on.
    var ppp = 3; // Post per page

    $("#more_posts").on("click",function(){ // When btn is pressed.
        $("#more_posts").attr("disabled",true); // Disable the button, temp.
        $.post(ajaxUrl, {
            action:"more_post_ajax",
            offset: (page * ppp) + 1,
            ppp: ppp
        }).success(function(posts){
            page++;
            $(".name_of_posts_class").append(posts); // CHANGE THIS!
            $("#more_posts").attr("disabled",false);
        });

   });

//</script>

Custom Ajax Handler (Server-side) PHP - Put this in the functions.php file.

function more_post_ajax(){
    $offset = $_POST["offset"];
    $ppp = $_POST["ppp"];
    header("Content-Type: text/html");

    $args = array(
        'post_type' => 'post',
        'posts_per_page' => $ppp,
        'cat' => 1,
        'offset' => $offset,
    );

    $loop = new WP_Query($args);
    while ($loop->have_posts()) { $loop->the_post(); 
       the_content();
    }

    exit; 
}

add_action('wp_ajax_nopriv_more_post_ajax', 'more_post_ajax'); 
add_action('wp_ajax_more_post_ajax', 'more_post_ajax');