Post Type archive incorrectly identified as "home"

[michaelhall]

Issue

If you go to a post type archive via GET parameters ("?post_type[]=post&post_type[]=page"), then the WP_Query incorrectly identifies the location as home.

Reason fix is required

Causes incorrect templates to be used in some themes.

Steps to reproduce

1. Setup wordpress
2. Add the following to your theme functions file

   add_action('init', function () {
       // allow archives on the main post types
       global $wp_post_types;
   
       $wp_post_types['post']->has_archive = true;
       $wp_post_types['page']->has_archive = true;
   });
   add_action('parse_query', function(&$query) {
       // just testing for information
       if ($query->is_main_query()) {
           var_dump($query);
       }
   });
   

3. Go to your wordpress home in your browser
4. Add "?post_type[]=post&post_type[]=page"
   • Note that this works for any post types
   • Also note that "has_archive" on the post types does not matter

Expected Results

• "is_home" is set to false
• "is_archive" is set to true
• "is_post_type_archive" is set to true

Actual Results

• "is_home" is set to true
• "is_archive" is set to false
• "is_post_type_archive" is set to false

Other Notes

• The "post" type has "has_archive" set to false by default, should consider changing it to true
• If a single post_type is set in the URL that has "has_archive" set to false, then the template is the home page, but the query uses the selected post_type anyway
  • eg. Go to homepage with posts feed, then add "?post_type=page", the homepage will then give a feed of pages instead of posts

[michaelhall]

Patch file containing part of a possible fix for the issue

[michaelhall]

I have provided a patch file that helps with the issue, but I believe that it does not appropriately cover all of the cases

[wonderboymusic]

I think what could happen is - when there is an array of post_types, is_archive could be true. That's it. Although, I foresee breakage.

If you made a post_type called News and wanted your homepage to show array( 'news', 'post' ) by filtering pre_get_posts, it currently is. Setting another flag would cause it to load archive.php.

[wonderboymusic]

Thanks for the report, but I think this is a no-go because of guaranteed breakage. This may have been an oversight or error in the original implementation of custom post types.

Closing as maybelater - someone can reopen if they feel this can be done in back compat way.

[nacin]

This is actually by design. Post type archives are designed to be for a single post type. Otherwise, ?post_type in a URL is no different than any other query string designed to alter a blog's results (like ?order=asc). We probably could load archive.php in this case and not break a ton, but I'd rather not risk it. This is less of a maybelater than a by-design. If you want to enforce a particular template, you can do so.

[SergeyBiryukov]

Related: #18114, #24473, #25143.