[wp-trac] [WordPress Trac] #42878: PHP notice when a post has a term from a "numeric" taxonomy

[WordPress Trac]

#42878: PHP notice when a post has a term from a "numeric" taxonomy
--------------------------+-----------------------------
 Reporter:  strategio     |      Owner:
     Type:  defect (bug)  |     Status:  new
 Priority:  normal        |  Milestone:  Awaiting Review
Component:  Taxonomy      |    Version:  4.9.1
 Severity:  normal        |   Keywords:
  Focuses:                |
--------------------------+-----------------------------
 This happens when the taxonomy name is numerical like "123456" for
 instance.

 '''Steps to reproduce:'''

 - After WP installation, add the following snippet to the theme's
 functions.php.

 {{{#!php
 <?php
 function wpmltm_2077_create_taxonomy() {
         $labels = array(
                 'name'          => _x( '123456', 'taxonomy general name',
 'textdomain' ),
                 'singular_name' => _x( '123456', 'taxonomy singular name',
 'textdomain' ),
         );

         $args = array(
                 'hierarchical'      => true,
                 'labels'            => $labels,
                 'show_ui'           => true,
                 'show_admin_column' => true,
                 'query_var'         => true,
                 'rewrite'           => array( 'slug' => 'xyz' ),
         );

         register_taxonomy( '123456', array( 'post' ), $args );
 }
 add_action( 'init', 'wpmltm_2077_create_taxonomy' );
 }}}

 - Go to Posts -> 123456 and add a new term "Test term".
 - Add a new post with the term "Test term" for taxonomy 123456 and click
 on "Publish".
 - Go to Posts
 => The PHP notice below is thrown.


 {{{
 ( ! ) Notice: Trying to get property of non-object in wp-includes\post.php
 on line 6161
 Call Stack
 #       Time    Memory  Function        Location
 1       0.0057  466920  {main}( )       ...\edit.php:0
 2       0.4055  25649896        WP_Posts_List_Table->prepare_items( )
 ...\edit.php:180
 3       0.4055  25649968        wp_edit_posts_query( ??? )      ...\class-
 wp-posts-list-table.php:136
 4       0.4069  25658096        wp( ??? )       ...\post.php:1073
 5       0.4069  25658120        WP->main( ??? ) ...\functions.php:960
 6       0.4097  25683376        WP->query_posts( )      ...\class-
 wp.php:715
 7       0.4097  25683440        WP_Query->query( ??? )  ...\class-
 wp.php:599
 8       0.4097  25683384        WP_Query->get_posts( )  ...\class-wp-
 query.php:3222
 9       0.4234  25851048        wp_queue_posts_for_term_meta_lazyload( ???
 )    ...\class-wp-query.php:3002
 }}}

 *Debugging:*
 - The actual value of `$term` at line 6161 is `null`.
 - The root cause is in `WP_Term::get_instance` where we have a strict
 comparison between the taxonomy name. On one side, we have an integer and
 on the other side we have a numerical string.

 This is because the taxonomies are stored in an array and the key is the
 taxonomy slug (which can be numerical).

 Here's PHP doc [http://php.net/manual/en/language.types.array.php]:
 > Strings containing valid decimal integers, unless the number is preceded
 by a + sign, will be cast to the integer type. E.g. the key "8" will
 actually be stored under 8. On the other hand "08" will not be cast, as it
 isn't a valid decimal integer.

--
Ticket URL: <https://core.trac.wordpress.org/ticket/42878>
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