src/admin/class-papi-admin-columns.php
public function pre_get_posts( WP_Query $query ) {
		global $pagenow;

		if ( $pagenow === 'edit.php' && ! is_null( papi_get_qs( 'page_type' ) ) ) {
			if ( papi_get_qs( 'page_type' ) === 'papi-standard-page' ) {
				$query->set( 'meta_query', [
					[
						'key'     => papi_get_page_type_key(),
						'compare' => 'NOT EXISTS'
					]
				] );
			} else {
				$query->set( 'meta_key', papi_get_page_type_key() );
				$query->set( 'meta_value', papi_get_qs( 'page_type' ) );
			}
		}

		// Order query result by entry type.
		if ( $query->get( 'orderby' ) === 'entry_type' ) {
			$query->set( 'meta_key', papi_get_page_type_key() );
			$query->set( 'orderby', 'meta_value' );
		}

		return $query;
	}
public function pre_get_posts( WP_Query $query ) {
		global $pagenow;

		if ( $pagenow === 'edit.php' && ! is_null( papi_get_qs( 'page_type' ) ) ) {
			if ( papi_get_qs( 'page_type' ) === 'papi-standard-page' ) {
				$query->set( 'meta_query', [
					[
						'key'     => papi_get_page_type_key(),
						'compare' => 'NOT EXISTS'
					]
				] );
			} else {
				$query->set( 'meta_key', papi_get_page_type_key() );
				$query->set( 'meta_value', papi_get_qs( 'page_type' ) );
			}
		}

		// Order query result by entry type.
		if ( $query->get( 'orderby' ) === 'entry_type' ) {
			$query->set( 'meta_key', papi_get_page_type_key() );
			$query->set( 'orderby', 'meta_value' );
		}

		return $query;
	}
Filter posts on load if `page_type` query string is set.

@param  WP_Query $query

@return WP_Query