WP: Add Custom Post types to main Query.

functions.php

<?php

if ( ! function_exists( 'ucc_add_cpts_to_pre_get_posts' ) ) {
function ucc_add_cpts_to_pre_get_posts( $query ) {
	if ( $query->is_main_query() && ! is_post_type_archive()  && ! is_singular() && ! is_404() ) {
		$my_post_type = get_query_var( 'post_type' );
		if ( empty( $my_post_type ) ) {
			$args = array(
				'exclude_from_search' => false,
				'public' => true,
				'_builtin' => false
			);
			$output = 'names';
			$operator = 'and';
			$post_types = get_post_types( $args, $output, $operator );
			
			// Or uncomment and edit to explicitly state which post types you want.
			// $post_types = array( 'event', 'location' );
	
			// Add 'link' and/or 'page' to array() if you want these included.
			// array( 'post', 'link', 'page' ), etc.
			$post_types = array_merge( $post_types, array( 'post' ) );
			$query->set( 'post_type', $post_types );
		}
	}
} }
add_action( 'pre_get_posts', 'ucc_add_cpts_to_pre_get_posts' );

/*
	Doing it wrong in so many different ways:
		http://gist.github.com/1695492
		http://gist.github.com/1695498
		http://gist.github.com/1695504
*/

/*
	Copyright 2012 Jennifer M. Dodd <jmdodd@gmail.com>
	Released under the GPLv2 (or later).
*/

?>