How to Use WP_Query to Filter WordPress Taxonomies

gitbox 2025-06-16

Understanding the WP_Query Class

WordPress is one of the most widely used open-source content management systems (CMS), and its powerful taxonomy and tagging features help organize articles and pages effectively. When managing a large volume of posts, you might need to use custom queries to filter information from taxonomies. This article will guide you on how to use the WP_Query class and its parameters to filter taxonomies.

What is WP_Query?

WP_Query is the core class in WordPress for querying various content from the database. It allows you to query posts, pages, attachments, and custom content types with flexibility. With this class, you can customize query parameters to retrieve content that meets specific criteria.

In this article, we will focus on how to use WP_Query to filter posts from specific taxonomies. With WP_Query, you can filter posts just like you would directly query the database.

Filtering a Specific Taxonomy

WP_Query supports a parameter called tax_query, which allows you to filter posts from specific taxonomies. The tax_query parameter is an array of arrays, enabling you to filter posts based on one or more criteria.

Here's an example of how to use WP_Query to filter posts from a specific category:

$args = array(
    'post_type' => 'post',
    'posts_per_page' => 10,
    'tax_query' => array(
        array(
            'taxonomy' => 'category',
            'field' => 'slug',
            'terms' => 'news',
        ),
    ),
);
$query = new WP_Query($args);

In this query, we specify a few key parameters:

post_type: The type of content we want to query—in this case, we are querying 'post' (articles).
posts_per_page: The number of posts to display per page; here we set it to 10.
tax_query: The filtering criteria specifying the taxonomy ('category') and the term ('news') to filter by.

This query will return all posts belonging to the "news" category.

Multiple Filter Conditions

The tax_query parameter also allows you to apply multiple filters, enabling you to query more precise posts. You can add additional filters by adding extra arrays to the tax_query parameter. Here's an example that queries custom taxonomies:

$args = array(
    'post_type' => 'post',
    'posts_per_page' => 10,
    'tax_query' => array(
        'relation' => 'OR',
        array(
            'taxonomy' => 'category',
            'field' => 'slug',
            'terms' => 'news',
        ),
        array(
            'taxonomy' => 'custom_category',
            'field' => 'slug',
            'terms' => 'featured',
        ),
    ),
);
$query = new WP_Query($args);

In this example, we set the relation parameter to 'OR', which means the query will return posts that meet either of the conditions (belonging to the "news" category or the "featured" custom category).

Conclusion

Through this article, you've learned how to use WP_Query's tax_query parameter to filter posts from specific taxonomies. We covered how to filter posts based on a single taxonomy, as well as how to apply multiple filter conditions for more complex queries. Whether you're dealing with default taxonomies or custom taxonomies, WP_Query provides you with powerful filtering capabilities.

How to Use WP_Query to Filter WordPress Taxonomies