How to use pre_get_posts filter in WordPress

pre_get_posts filter

Note: If using conditional tags, use the method versions within the passed instance (e.g. $this->is_main_query() instead of is_main_query()). This is because the functions like is_main_query() test against the global $wp_query instance, not the passed one.

To use the pre_get_posts filter, first you have to register it using add_filter. You can write this code into functions.php of your activated theme or in a custom WordPress Plugin.

We at WePlugins, always prefer to create a custom WordPress Plugin while using hooks so nothing breaks when you update your WordPress Theme in the future.

In the below live example, we have defined a function modify_pre_get_posts_defaults which takes 1 parameter and we registered it using add_filter. The first parameter pre_get_posts is the name of the hook, the second parameter modify_pre_get_posts_defaults is the name of the function which needs to be called, the third parameter is the priority of calling the hook if the same hook is used multiple times, and the last parameter is the number of arguments (if any) to be passed in the registered function.

Sometimes, you have to remove a registered hook, so you can use remove_filter to remove the pre_get_posts filter.

Parameters

Below the 1 parameter is required to use this hook.

• $query : (WP_Query) The WP_Query instance (passed by reference).

Live Examples

Example 1: Target Main Category Query with Conditional Tags

This example modifies the main query for category archives to set the number of posts per page to 15.

    function weplugins_target_main_category_query_with_conditional_tags( $query ) {
        if ( ! is_admin() && $query->is_main_query() ) {
            if ( is_category() ) {
                $query->set( 'posts_per_page', 15 );
            }
        }
    }
    add_filter( 'pre_get_posts', 'weplugins_target_main_category_query_with_conditional_tags' );
    

Example 2: Modify pre_get_posts Defaults

Below is an example of how you can use this hook to modify the query variable according to your website requirements.

    function weplugins_modify_pre_get_posts_defaults($query) {
        // Update the $query variable according to your website requirements.
        return $query;
    }
    add_filter( 'pre_get_posts', 'weplugins_modify_pre_get_posts_defaults', 10, 1 );
    

Example 3: Remove a Hook Callback

To remove a hook callback, use the example below. Ensure you provide the same callback function name, priority, and number of arguments while removing the hook callback.

    remove_filter( 'pre_get_posts', 'weplugins_modify_pre_get_posts_defaults', 10, 1 );
    

Contact Us

If you need customization or have any trouble using this hook, Contact Us and we’d be happy to assist you.