Iterating over correct number of wordpress posts from category + custom post type

Question

Our wordpress post loop combines and displays posts from a specific category and a custom post type. This works, but is not displaying all posts. I believe that the post loop is iterating over the number of posts in the specific category, not the number of posts in the specific category + the number of posts in the custom post type. How can I ensure that the correct number of posts are being displayed?

<?php
/*
Template Name: Articles & Cases
*/
get_header(); ?>
<div class="center-holder">
    <div id="content">
        <?php while ( have_posts() ) : the_post(); ?>
            <?php the_title( '<h1>', '</h1>' ); ?>
            <?php the_post_thumbnail( 'full' ); ?>
            <?php the_content(); ?>
            <?php if ( $cats = get_field( 'category' ) ) : ?>
                <?php
                    $args = array(
                        'post_type' => array( 'post' ),
                        'category__in' => $cats,
                        'fields' => 'ids',
                    );

                    $articles = new WP_Query( $args );
                    wp_reset_postdata();

                    $args = array(
                        'post_type' => array( 'case_study' ),
                        'fields' => 'ids',
                        );
                    $case_study = new WP_Query( $args );
                    wp_reset_postdata();

                    $all_posts_ids = array_merge( $articles->posts, $case_study->posts );

                    $paged = get_query_var( 'paged' ) ? get_query_var( 'paged' ) : 1;
                    $args = array(
                        'post_type' => array( 'post', 'case_study' ),
                        'post__in' => $all_posts_ids,
                        'paged' => $paged,
                        );                  

                    query_posts( $args );
                ?>
                <?php if ( have_posts() ) : ?>
                    <?php while ( have_posts() ) : the_post(); ?>
                        <?php get_template_part( 'blocks/content', get_post_type() ); ?>
                    <?php endwhile; ?>
                    <?php get_template_part( 'blocks/pager' ); ?>
                <?php else: ?>
                    <?php get_template_part( 'blocks/not_found' ); ?>
                <?php endif; wp_reset_query(); ?>

            <?php endif; ?>
        <?php endwhile; ?>
    </div>
    <?php get_sidebar( 'blog' ); ?>
</div>
<?php get_footer(); ?>

Answer 1

There is a number of things you're doing wrong.

You are using a page template, and then are looping using the loop. This probably pulls all posts, as the last fallback for page template is index.php (as seen in the diagram here).

Then you are making 3 additional queries while in the loop (so for every post you loop you make 3 extra queries).

And the last query, you are using query_posts() which is overriding the main query. Just don't ever use that.

So the plan of attack should be:

1. What do I want to show?

2. How and where do I want to show it?

3. What do I need to do to achieve this?

4. Start writing things needed to achieve this.

5. ???

6. Profit!!!

If you want to control specific taxonomy, use $taxonomy.php template (with $taxonomy being the name of the taxonomy.).

Hope this helps.