How to order posts in an arbitrary order?

Question

I need to list posts in a very specific order that has nothing to do with the date of the posts or the title, or anything WordPress can figure out for me. I need this order to be used when I list posts in a category and on the category archive page itself.

Is it possible to do something like this, were $idlist was an array of post ids in the order I want, and it could loop through each one?

  <?php query_posts(post_id=$idlist); ?>
  <?php the_permalink(); ?> etc...

Answer 1

First off, query_posts is terrible doesn't use it. It does all kinds of fun things like mess up the very useful conditional tags like is_singular and the like as well as mess up pagination.

Short of hooking into the posts_orderby filter and writing some custom order by SQL, your best bet is to use the post__in argument combined with the post__in orderby argument that was added in WP 3.5.

Example:

<?php
$custom_query = new WP_Query(array(
    'post__in'  => array(1, 2, 4, 5, /* whatever your post ID's are here */),
    'orderby'   => 'post__in',
));

while ($custom_query->have_posts()) {
    $custom_query->the_post();
    // use the normal template tags here
    ?>
    <a href="<?php the_permalink(); ?>" title="<?php the_title_attribute(); ?>"><?php the_title(); ?></a>
    <?php
}

// restore the original query
wp_reset_query();