[wp-trac] [WordPress Trac] #19653: Order by meta field forces ignore of null records

[WordPress Trac]

#19653: Order by meta field forces ignore of null records
-------------------------+-----------------------------
 Reporter:  tomauger     |      Owner:
     Type:  enhancement  |     Status:  new
 Priority:  normal       |  Milestone:  Awaiting Review
Component:  Query        |    Version:
 Severity:  normal       |   Keywords:
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 When doing a sort on posts with a meta value, the way the SQL is currently
 generated in meta.php creates a condition where records that DO NOT have
 the queried meta value are excluded from the results. This may or may not
 be the desired behaviour, but we don't give developers the choice without
 resorting to custom queries or manual rewrites of large swathes of the
 $clauses array.

 The issue: the way WP_Meta_Query->get_sql() creates the join on the meta
 key is by setting an inner join on wp_postmeta and then adding the key
 test to the where clause.

 I would suggest writing an outer (left) join on wp_postmeta, with the key
 condition in the join. This would also eliminate any potential future
 ambiguity if, for example, you are sorting on one meta key but filtering
 on another, since the key condition would be within the join clause, not
 the where clause:


 {{{
 LEFT JOIN wp_postmeta ON wp_posts.ID = wp_postmeta.post_id AND
 wp_postmeta.meta_key = 'my_custom_field_name'
 }}}


 Related to ticket 18158 [http://core.trac.wordpress.org/ticket/18158] is
 the question of how we expose this to the developer in the query API.


 {{{
 'meta_key' => self::get_meta_key( 'my_custom_field_name' ),
 'orderby' => 'meta_value',
 'exclude_empty_meta' => false
 }}}


 If this gets any traction I would be happy to submit a patch.

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Ticket URL: <http://core.trac.wordpress.org/ticket/19653>
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