[wp-trac] [WordPress Trac] #39926: wp_get_object_terms should return WP_Error on wrong fields argument or use a sane default

[WordPress Trac]

#39926: wp_get_object_terms should return WP_Error on wrong fields argument or use
a sane default
--------------------------+-----------------------------
 Reporter:  BjornW        |      Owner:
     Type:  defect (bug)  |     Status:  new
 Priority:  normal        |  Milestone:  Awaiting Review
Component:  Taxonomy      |    Version:  trunk
 Severity:  normal        |   Keywords:
  Focuses:                |
--------------------------+-----------------------------
 wp_get_object_terms( $object_ids, $taxonomies, $args ) accepts object_ids,
 taxonomies and as last option extra arguments as an array. One of the
 extra arguments in the $args array is the fields option.

 I used the field value 'term_id' (erroneously) assuming this would return
 the term_ids. However this did not work. wp_get_object_terms returned an
 empty array and in my error log I noticed this SQL error message:

 {{{
 WordPress database error You have an error in your SQL syntax; check the
 manual that corresponds to your MySQL server version for the right syntax
 to use near 'FROM wp_terms AS t  INNER JOIN wp_term_taxonomy AS tt ON
 t.term_id = tt.term_id ' at line 1 for query SELECT   FROM wp_terms AS t
 INNER JOIN wp_term_taxonomy AS tt ON t.term_id = tt.term_id INNER JOIN
 wp_term_relationships AS tr ON tr.term_taxonomy_id = tt.term_taxonomy_id
 WHERE tt.taxonomy IN ('product') AND tr.object_id IN (449, 427) ORDER BY
 t.name ASC
 }}}

 After consulting the source of the wp_get_object_terms I noticed that
 'term_id' is not a valid fields value. However I would have expected
 wp_get_object_terms() to return a WP_Error object instead of creating
 erroneous SQL code.

 The following are valid field option values:

  * all - Default : all matching term's objects will be returned
  * ids : term's ids will be returned
  * names : term's names will be returned
  * slugs : term's slugs will be returned
  * all_with_object_id : all matching term's objects will be returned
  * tt_ids : term's taxonomy's ids will be returned

 [https://codex.wordpress.org/Function_Reference/wp_get_object_terms See
 wp_get_object_terms() docs on the Codex]


 === Proposed solution
 Due to [https://core.trac.wordpress.org/browser/trunk/src/wp-includes
 /class-wp-term-query.php#L581 this switch statement] invalid or an empty
 fields value will result in an empty SELECT SQL query in this
 [https://core.trac.wordpress.org/browser/trunk/src/wp-includes/class-wp-
 term-query.php#L650 codeblock]

 My proposal is to add a default clause to the
 [https://core.trac.wordpress.org/browser/trunk/src/wp-includes/class-wp-
 term-query.php#L581 switch statement] which defaults to using the 'all'
 case value.

 This seems to adhere to the functionality as well as the spirit of the
 rest of the WP_Term_Query class code. As far as I know it should be
 backwards compatible as well.

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Ticket URL: <https://core.trac.wordpress.org/ticket/39926>
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