how do i remove posts from a WP_Query so the pagination is right?

Question

I'm using a custom post type and showing 20 of them per page on the homepage. I'm using QP_Query.

One custom field for the custom post type (called mixtapes) is a checkbox called "unreleased" (set to true/false), and its basically a post that i dont want to include in the loop.

So far I put a conditional if inside the while loop to display only if 'unreleased' isnt set to 'true', but the problem is its (obviously) not applying to the loop itself, so as a result... the pagination 'sees' 40 posts (2 pages) when really theres only 1 unreleased album (which should be 1 page, but 2 pages show up). on the 2nd page, is no results.

Likewise when i want to show the 'top 10' albums which ARE released, it actually shows only 9 because the one unreleased one hasnt been removed from the actual loop, only conditionally 'hidden' after the fact.

How might i work this out so the loop keeps track of the posts that have been removed given a certain custom_field condition?

Thnkas

Answer 1

Rather than querying all posts and then only displaying those that match the criteria, query for posts that match the criteria. WP_Query allows you to do just that with its meta-key/meta-value attributes.

For instance, to get posts where the custom field unreleased is to 'false', somewhere before the loop:

global $wp_query;
$customField = array( 'meta_key' => 'unreleased', 'meta_value' => 'false' );
$args = array_merge( $wp_query->query,$customField);
query_posts( $args );

This isn't the most effecient way of doing things, but it is the simplest. We merge to the meta key/value query with the existing query (this includes pagination arguments).

You'll have to decide if WP_Query and query_posts is the right thing to use here (if it's not the main query on the page then you should get using get_posts instead - it accepts the same parameters).

Note: If you decide to use get_posts or WP_Query (but not with query_posts which alters the main query) then you shouldn't be merging. (If you're not sure which you should be using see this, now officially, 'great answer' :D)