Searching with explicit post types unsets page post type

[GaryJ]

Tested on WP 3.2.1, Twenty Eleven with no plugins, multisite.

If I explicitly limit a search query via a GET request using an array of post_type values, the post_type for page is automatically excluded.

To reproduce:

• Do a search on a WP install (perhaps through a modified search form), such that the URL is like: ​http://example.com/?post_type[]=post&post_type[]=page&post_type[]=attachment&s=Test

or

​http://example.com/?post_type[]=post&post_type[]=page&post_type[]=book&s=Test

That's searching for "Test" on post, page and attachment/book post types.

• Adding the following to a theme's functions.php:

  add_filter( 'pre_get_posts', 'wpcpt_search' );
  /**
   *
   * @param array $query
   */
  function wpcpt_search( $query ) {
  
  	if ( ! $query->is_search )
  		return $query;
  
  	print_r( $query->query_vars );
  
  	return $query;
  
  }
  

That spits out (and seemingly confirmed via the values shown in the Debug Bar plugin) the following at the beginning:

  Array ( [s] => Test [post_type] => Array ( [0] => post [2] => attachment ) 

and only returns results for posts and attachments (or books). The fact that key 1 is missing makes me think that page was in the array at some point, but it's been unset, but I can't see where, or why, this might be done.

(When no post_type is set, giving a post_type of 'any', which in turn gives all of the non-excluded_from_search post types, then page is one of the array values, and the search results correctly include pages.)

Replying to GaryJ:

The fact that key 1 is missing makes me think that page was in the array at some point, but it's been unset, but I can't see where, or why, this might be done.

http://core.trac.wordpress.org/browser/tags/3.2.1/wp-includes/class-wp.php#L280

Pages are not publicly queryable (see [18234], #17040), so they are excluded.

Well, I'll be. I looked at that post type registration and missed the publicly_querable line. Thank you.

In that case then, why does the Page appear in the search results when there's no post_type set? The Debug Admin Bar gives part of the Query SQL as:

...AND wpgt_posts.post_type IN ('post', 'page', 'attachment', 'class', 'function', 'hook', 'book')...

It's this discrepancy which is odd.

Non-publicly queryable post types are only excluded from post type queries, that doesn't prevent them to appear in a regular search results (without post_type constraints).

Perhaps they shouldn't be excluded when searching, though. Here's a patch for that.

Edited. (Invalid question after re-reading the above comment several times.)