Wordpress Query order by custom field missing post

问题:

This is my current query:

query_posts(array_merge(array('tag' => $pagetag,'meta_key'=>priority,'orderby' =>meta_value, 'order' =>'ASC','paged' => get_query_var('paged'))));

My problem is that the query shows me only the post that has values for my 'meta_key' meaning that 'priority' is not NULL. How can I improve this query so that it will still orderby my meta_key but will show all the posts that aren't NULL as well?

Thanks in advance!

回答1:

The problem is that WordPress adds an INNER JOIN to the wp_postmeta table as soon as you mention meta_key in your conditions. One way around the problem is to add a filter on the order by clause, something like this:

function so_orderby_priority($original_orderby_statement) {
    global $wpdb;

    return "(SELECT $wpdb->postmeta.meta_value
               FROM $wpdb->postmeta
              WHERE $wpdb->posts.ID = $wpdb->postmeta.post_id
                AND $wpdb->postmeta.meta_key = 'priority') ASC";
}

add_filter('posts_orderby', 'so_orderby_priority');

query_posts(
    array(
        'tag' => $pagetag,
        'paged' => get_query_var('paged')
    )
);

remove_filter('posts_orderby', 'so_orderby_priority');

Note MySQL sorts NULLs first - if you want them sorted last, try something like this (assuming all your priorities come before ZZZZZ alphabetically):

function so_orderby_priority($original_orderby_statement) {
    global $wpdb;

    return "IFNULL(
               (SELECT $wpdb->postmeta.meta_value
                  FROM $wpdb->postmeta
                 WHERE $wpdb->posts.ID = $wpdb->postmeta.post_id
                   AND $wpdb->postmeta.meta_key = 'priority'),
                'ZZZZZ') ASC";
}

Edit

Here's a bit more explanation, which assumes you understand SQL at least a bit.

Your original query_posts resulted in the following query running against the database:

SELECT wp_posts.*
FROM   wp_posts
       INNER JOIN wp_term_relationships ON ( wp_posts.id = wp_term_relationships.object_id )
       INNER JOIN wp_postmeta ON ( wp_posts.id = wp_postmeta.post_id )
WHERE  1 = 1
       AND ( wp_term_relationships.term_taxonomy_id IN ( 3 ) )
       AND wp_posts.post_type = 'post'
       AND ( wp_posts.post_status = 'publish'
              OR wp_posts.post_status = 'private' )
       AND ( wp_postmeta.meta_key = 'priority' )
GROUP  BY wp_posts.id
ORDER  BY wp_postmeta.meta_value ASC
LIMIT  0, 10; 

That INNER JOIN wp_postmeta is what removed any posts without a priority from your results.

Removing the meta_* related conditions from your query_posts:

query_posts(
    array(
        'tag' => $pagetag,
        'paged' => get_query_var('paged')
    )
);

solved that problem, but the sort order is still wrong. The new SQL is

SELECT wp_posts.*
FROM   wp_posts
       INNER JOIN wp_term_relationships ON ( wp_posts.id = wp_term_relationships.object_id )
WHERE  1 = 1
       AND ( wp_term_relationships.term_taxonomy_id IN ( 3 ) )
       AND wp_posts.post_type = 'post'
       AND ( wp_posts.post_status = 'publish'
              OR wp_posts.post_status = 'private' )
GROUP  BY wp_posts.id
ORDER  BY wp_posts.post_date DESC
LIMIT  0, 10; 

The posts_orderby filter allows us to change the ORDER BY clause: wp_posts.post_date DESC gets replaced by what the filter returns. The final SQL becomes:

SELECT wp_posts.*
FROM   wp_posts
       INNER JOIN wp_term_relationships ON ( wp_posts.id = wp_term_relationships.object_id )
WHERE  1 = 1
       AND ( wp_term_relationships.term_taxonomy_id IN ( 3 ) )
       AND wp_posts.post_type = 'post'
       AND ( wp_posts.post_status = 'publish'
              OR wp_posts.post_status = 'private' )
GROUP  BY wp_posts.id
ORDER  BY (SELECT wp_postmeta.meta_value
           FROM   wp_postmeta
           WHERE  wp_posts.id = wp_postmeta.post_id
                  AND wp_postmeta.meta_key = 'priority') ASC
LIMIT  0, 10 

which does what you're after.

回答2:

I needed to perform a similar task on the users.php page for a custom column I added and used the following code that I modified from Hobo

add_action('pre_user_query', 'qd_users_column_orderby');

function qd_users_column_orderby($userquery){
  if('my_last_login'==$userquery->query_vars['orderby']) { //check if my cusomt meta_key is the column being sorted

    global $wpdb;

    $userquery->query_orderby = " ORDER BY(SELECT $wpdb->usermeta.meta_value
        FROM $wpdb->usermeta
        WHERE $wpdb->users.ID = $wpdb->usermeta.user_id
        AND $wpdb->usermeta.meta_key = 'my_last_login') ".($userquery->query_vars["order"] == "ASC" ? "asc " : "desc ")." , wp_users.user_login ".($userquery->query_vars["order"] == "ASC" ? "asc " : "desc ");
  }
}

Hopefully this helps somebody in need of this information.

In an effort of being throughout, the remainder of the necessary code to complete my individual task is below.

add_filter('manage_users_columns', 'qd_add_user_login_column');

function qd_add_user_login_column($columns) {
  $columns['my_last_login'] = 'Last Logged In';
  return $columns;
}

add_action('manage_users_custom_column',  'qd_show_user_login_column_content', 10, 3);

function qd_show_user_login_column_content($value, $column_name, $user_id) {
  $user = get_userdata( $user_id );
  if ( 'my_last_login' == $column_name ){
    $lastLogin = get_the_author_meta('my_last_login', $user_id);
    if(!$lastLogin){
      return "Never";
    }else{
      date_default_timezone_set(get_option('timezone_string'));
      return date('m/d/y g:ia', $lastLogin); 
    }
  }
  return $value;
}

add_filter( 'manage_users_sortable_columns', 'qd_users_table_sorting' );

function qd_users_table_sorting( $columns ) {
  $columns['my_last_login'] = 'my_last_login';
  return $columns;
}

回答3:

The Issue: Sorting by a custom field without excluding posts that don't have a value set for that custom field.

Hobo's answer explains this well. Here I'm just going to offer a simpler alternative that ended up being easier in my case (Please note this won't work correctly if pagination is needed).

I decided to do the sorting in PHP after the query is made. The nice part is that I have better control over where the posts with null values end up (I wanted them to show up last).

$query = new WP_Query($args); 

//sort by rank
function customSort($a, $b)
{
    $a = get_field("sort_ranking", $a);
    $b = get_field("sort_ranking", $b);

    //handle nulls
    $a = is_numeric($a) ? $a : 9999;
    $b = is_numeric($b) ? $b : 9999;

    if ($a == $b) return 0;
    return ($a < $b) ? -1 : 1;
 }
 usort($query->posts, "customSort");

Here I have a numeric custom field called sort_ranking and I'm using it to sort ASC. Posts with a null value for this field are assigned 9999 so that they end up at the end. (Note: I'm using ACF, hence the get_field function)

Hope this helps someone!

回答4:

The easiest way to do this is to insert the custom field using save_post action, so every post published will have its own meta_key with a default value.

Use a MySQL query for add post_meta to all posts has not the meta. Thats it.

If you/anyone need code help on this, just reply :)

UPDATE

As Timusan asked, add this code in your functions.php file after changing the meta-key name :

add_action('save_post', 'sidati_post_views_metakey');

function sidati_post_views_metakey ($post_id){

    /*
    * $post_id = is the post ID
    * 'sidati_post_views' => is your metakey name (sidati is prefix always nice to add your prefix)
    * 0 => the inital value
    * true => (bool) add true if you want this metakkey become unique
    */

    add_post_meta($post_id, 'sidati_post_views', 0, true);

}


// THIS ACTION MUST RUN ONLY ONE TIME
add_action('init', 'sidati_allposts_must_have_this');

function sidati_allposts_must_have_this(){

    /* Call the WordPress DataBase class */
    global $wpdb; 

    /* This Query will get us all the posts and pages without "sidati_post_views" metakey. */
    $ids = $wpdb->get_row("SELECT ID FROM wpdb->posts WHERE post_type IN ('post', 'page') AND post_status = 'publish' AND ID NOT IN (SELECT post_id FROM $wpdb->postmeta WHERE meta_key = 'sidati_post_views')");

    /* After get all posts/pages, now you need to add the meta keys (this may take a few munites if you have many posts/pages)*/
    foreach ($ids as $post_id) {
        add_post_meta($post_id, 'sidati_post_views', 0, true);
    }
}