Advanced Custom Fields Query with Different Values of the Same Key

Question

I have a custom post type set up with Advanced Custom Fields. I would like to display and order my posts in groups. The groups are states of the United States, so I have 50 groups.

Should I perform one query per state or is there a way to create one query that will cycle through all the different ( key : value ) (states) values and echo them out to the page in their respective groups?

    <?php 

        $posts = get_posts(array(
          'posts_per_page'  => -1,
          'post_type'     => 'school',
          'meta_key'    => 'state',
          'meta_value'  => 'Texas'
        ));

        if( $posts ): ?>

          <?php foreach( $posts as $post ): setup_postdata( $post ) ?>
            <li>
              <a href="<?php the_permalink(); ?>"><?php the_title(); ?></a>
            </li>
          <?php endforeach; ?>
        <?php wp_reset_postdata(); ?>
      <?php endif; ?>

This is the standard ACF query by meta value.

Answer 1

One option is to fetch all of the posts to a single array and filter that array 50 ways. This would only generate the one query:

$posts = get_posts(array(
      'posts_per_page'  => -1,
      'post_type'     => 'school'
    ));

To filter your array you would do something like this:

$this_state = "Texas";
$state_posts = array_filter($posts, function($results) use($this_state) {
                            return $results['state'] == $this_state;
                            }); 

From there, $state_posts should contain a subset of $posts where the State is Texas. Modify appropriately for each of your 50 groups.

This is untested but modeled on a very similar template I wrote last week.