[wp-trac] [WordPress Trac] #56992: The Loop displays incorrect data for queries started with `fields => 'id=>parent'`.

[WordPress Trac]

#56992: The Loop displays incorrect data for queries started with `fields =>
'id=>parent'`.
-------------------------------------------------+-------------------------
 Reporter:  peterwilsoncc                        |       Owner:
                                                 |  peterwilsoncc
     Type:  defect (bug)                         |      Status:  reopened
 Priority:  normal                               |   Milestone:  6.8
Component:  Query                                |     Version:  3.1
 Severity:  normal                               |  Resolution:
 Keywords:  2nd-opinion has-patch has-unit-      |     Focuses:
  tests dev-feedback                             |  performance
-------------------------------------------------+-------------------------

Comment (by SirLouen):

 Replying to [comment:31 peterwilsoncc]:
 > If it just affected `global $post`, I might be fine with that but it
 affects all the functions that are documented to the effect that "within
 the loop, this function will return the value of the [thing] of the global
 post" This includes:
 >
 > * `get_the_content()`
 > * `get_the_excerpt()`
 > * `get_the_title()`
 > * `get_the_time()`
 > * most other functions used in the loop and prefixed `get_` or `the_`

 I'm doing myself a lot of questions with this topic. And one of the
 biggest questions that comes to my mind is: Isn't a workaround, without
 touching the core code, to achieve the same results?

 Because the baseline is performant by default, but your "upgrade" hits
 significantly the performance. If someone is currently using the
 performant version (which is the mostly likely since the new version did
 not exist for ages), he will have his site affected by this patch.

 But if there is a workaround for your use-case that doesn't require the
 core "upgrade" then your site will be impacted, but the rest of the sites
 will remain untouched.

 When I'm asking for a use-case, I'm asking for a plugin, either an
 existing or a new one, that clearly requires this new upgrade and cannot
 achieve the result because of the lacking functionality.

 Here is my plugin, that is using the current version before this patch. It
 doesn't require the "upgrade" and it works as expected
 https://github.com/SirLouen/hierarchical-page-navigator

 Just remember that now it's being impacted by a 40% extra overhead with
 the current patch with no gains in functionality.

 A workaround that comes to my mind, to populate template functions with
 the original version could be done using
 [https://developer.wordpress.org/reference/functions/setup_postdata/
 setup_postdata]

 {{{#!php
 <?php

 $query = new WP_Query([
     'post_type' => 'page',
     'fields' => 'id=>parent',
     // Whatever else you want add to the query
 ]);

 while ($query->have_posts()) {
     $query->the_post();
     global $post;

     // And here you get full post object only when really needed
     if (is_numeric($post) || $post instanceof stdClass) {
         $post = get_post($post instanceof stdClass ? $post->ID : $post);
         setup_postdata($post);
     }

     // Now the template functions should work correctly
     the_title();
 }
 }}}

-- 
Ticket URL: <https://core.trac.wordpress.org/ticket/56992#comment:32>
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