Advanced custom fields: can't query posts by custom field - advanced-custom-fields

Question

I'm trying to query posts whose ACF field "show_on_frontpage" value is equal to "yes" (see definition of this field in screenshot below). As prescribed in ACF docs here's my code:
$args = array(
'posts_per_page' => -1,
'meta_key' => 'show_on_frontpage',
'meta_value' => 'yes'
);
$my_posts = new WP_Query($args);
if ($my_posts->have_posts()) {
while ($my_posts->have_posts()) : $my_posts->the_post();
if (get_field('show_on_frontpage')) the_field('show_on_frontpage'); ?>
endwhile;
}
This returns/displays nothing. If I used instead simply $args = array('posts_per_page' => -1); then I get all my posts and "yes" shows up for those that have "yes" as the value of their "show_on_frontpage" field.
What's wrong with my code?

Answer 1

According to this question/answer on the ACF forum:
https://support.advancedcustomfields.com/forums/topic/using-checkbox-fields-in-custom-queries/
It would be better to switch your checkbox field to a True/False field instead, since it appears that your checkbox group field only contains a single option.
Checkboxes are stored as serialized data and you’re not going to be able to use WP_Query to filter by a checkbox field.
If you use a true/false field then you can use WP_Query, the values of
a true/false field are 0 (zero) for false and 1 for true.
So if you switched your checkbox field to a True/False field, you would rewrite your code as follows:
$args = array(
'posts_per_page' => -1,
'meta_key' => 'show_on_frontpage',
'meta_value' => 1 /* or true */
);
$my_posts = new WP_Query($args);
if ($my_posts->have_posts()) {
while ($my_posts->have_posts()) : $my_posts->the_post();
/* My content for each post with the checkbox checked goes here */
endwhile;
}

Answer 2

This should work if you use the more recent meta_query => array() syntax:
$args = array(
'posts_per_page' => -1,
'meta_query' => array(
array(
'key' => 'show_on_frontpage',
'value' => 'yes',
'compare' => 'LIKE',
)
),
);
$my_posts = new WP_Query($args);
if ($my_posts->have_posts()) {
while ($my_posts->have_posts()) : $my_posts->the_post();
echo get_the_title();
// Post stuff
endwhile;
/* Restore original Post Data */
wp_reset_postdata();
}
Note that you need to give the post ID to the ACF helper functions get_field() & the_field() within the while loop.
See https://codex.wordpress.org/Class_Reference/WP_Query#Custom_Field_Parameters
On a wider note, this article calls into question the wisdom of using post_meta keys for this purpose and is worth a read: https://tomjn.com/2016/12/05/post-meta-abuse/. The article suggests using a custom taxonomy to achieve what you need - being better for performance.