This is How to Fix the Meta Query Posts by Sub Field Value ACF Issue
As a WordPress developer, you may have encountered the issue of querying posts by a sub-field value in Advanced Custom Fields (ACF). The standard approach of using a meta_query with an '=' comparison often doesn't work as expected, especially after the release of WordPress 4.8.3.
I spent a few hours on this problem and have a solution for you. In this blog post, I'll walk you through the steps to fix the Meta Query Posts by Sub Field Value ACF issue.
The Problem: Querying Posts by Sub Field Value
When working with ACF, you may need to query posts based on the value of a sub-field. For example, let's say you have a custom post type called "Manufacturers" and an ACF field called "cars" that has multiple sub-fields, such as "model" and "year".
You might want to retrieve all the manufacturers that have a car with the model "Audi". The standard approach would be to use a meta_query with an '=' comparison:
$args = array(
'post_type' => 'manufacturers',
'meta_query' => array(
array(
'key' => 'cars_%_model',
'value' => 'audi',
'compare' => '='
)
)
);
$query = new WP_Query($args);
However, this code often doesn't work as expected, especially after the WordPress 4.8.3 update. The issue is that the '=' comparison in the meta_query doesn't play well with the way ACF stores the data.
The Solution: Replace '=' with 'LIKE' Comparisons
The solution to this problem is to replace the '=' comparison with a 'LIKE' comparison. This can be done by setting up a custom filter that modifies the posts_where
clause of the query.
Here's the code to implement this solution:
function my_posts_where( $where ) {
$where = str_replace("meta_key = 'cars_", "meta_key LIKE 'cars_%'", $where);
return $where;
}
add_filter('posts_where', 'my_posts_where');
$args = array(
'post_type' => 'manufacturers',
'meta_query' => array(
array(
'key' => 'cars_%_model',
'value' => 'audi',
'compare' => '='
)
)
);
$query = new WP_Query($args);
Here's how it works:
- The
my_posts_where
function is a custom filter that replaces any occurrence of meta_key = 'cars_'
with meta_key LIKE 'cars_%'
.
- The
add_filter('posts_where', 'my_posts_where')
line adds the custom filter to the posts_where
clause of the query.
- The
$args
array remains the same, with the 'compare' => '='
clause.
This solution should work for you, regardless of the WordPress version you're using.
Understanding the Issue
The reason why the '=' comparison doesn't work as expected is due to the way ACF stores the data. When you have multiple sub-fields, ACF creates individual custom fields for each sub-field, with the sub-field name appended to the main field name.
For example, if you have a "cars" field with "model" and "year" sub-fields, ACF will create the following custom fields:
cars_0_model
cars_0_year
cars_1_model
cars_1_year
- and so on, for each car entry.
The '=' comparison in the meta_query expects an exact match, but the way ACF stores the data means that the field names don't always match exactly. The 'LIKE' comparison, on the other hand, allows for a more flexible match, which is why it works better in this scenario.
Conclusion
In this blog post, I've shown you how to fix the Meta Query Posts by Sub Field Value ACF issue. By setting up a custom filter to replace '=' comparisons with 'LIKE' comparisons, you can overcome the limitations of the default meta_query approach and effectively query posts based on sub-field values.
Remember, this solution is not specific to a particular WordPress version, so you can use it regardless of the version you're running. If you have any questions or need further assistance, feel free to reach out to me at Flowpoint.ai, where we specialize in providing data-driven solutions to help improve website conversion rates.
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