Pre_get_posts filter overwrites all search functionality

Question

So I have the out of the box wordpress 'Search' widget that I want to expand. I used the below filter to have the ability to search for my custom post types inside the widget:

add_filter( 'pre_get_posts', function($query) {
    if ($query->is_search) {
        $query->set('post_type', [
            'post', 'profile' ,'recipe', 'dish'
        ]);
    }
});

The problem that I discovered is that it overwrote ALL search items on the website, including the search box inside the admin panel 'Posts', where I was getting custom post type results although they didn't live there.

Does anyone know how to improve the search functionality on the search widget to include custom post types without overwriting ALL search boxes throughout the site?

Answer 1

That's easy, pre_get_posts applies to all queries, not just those on the frontend. So if you don't want it to run on admin queries, test if you're in the admin and exit early!

You might also want to verify that you're in the main query

add_filter( 'pre_get_posts', function( \WP_Query $query) {
    if ( is_admin() ) {
        return;
    }
    if ( ! $query->is_main_query() ) {
        return;
    }

Remember, pre_get_posts runs on all queries, regardless of where, be it admin, frontend, XMLRPC, REST API, etc. It will only run on the frontend if you tell it to only run on the frontend.