Retrieve posts from meta key

Question

I'm trying to query the list of posts using the meta_key but the result I got back was an empty array.

To write the data, I used the following codes:

$post_id = 2;
$user_key = 'ldp_system_follows_user_1';
$user_data_new = array(
    'followed'    => 'nofollowed'
);

update_post_meta($post_id, $user_key, $user_data_new);

The above code persisted the following in db when executing get_post_meta(post_id);

{
  "ldp_system_follows_user_1": [
    "a:1:{s:8:\"followed\";s:8:\"followed\";}"
  ]
}

I wanted to retrieve all the post ids that matches the meta data I wrote but it returned an empty array.

$args = array(
        'post_type'     => 'post',
        'post_status'   => 'publish',
        'meta_query'    => array(
                                array(
                                    'key'   => $user_key,
                                    'value' => $user_data_new,
                                    'compare'   => 'LIKE'
                                ))
    );

    return  get_posts($args);

Any help would be greatly appreciated.

UPDATE 1:

As suggested by phatskat, here are the SQL statement when I changed 'value' => 'follow' and 'value' => 'nofollow' respectively. However, I'm still getting the empty array back:

//'value' => $user_data_new,
"query": {
    "post_type": "post",
    "post_status": "publish",
    "meta_query": [
      {
        "key": "ldp_system_follows_user_1",
        "value": {
          "followed": "nofollowed"
        },
        "compare": "LIKE"
      }
    ]
  },


"request": "SELECT SQL_CALC_FOUND_ROWS  wp_posts.ID FROM wp_posts  INNER JOIN wp_postmeta ON ( wp_posts.ID = wp_postmeta.post_id ) WHERE 1=1  AND ( \n  ( wp_postmeta.meta_key = 'ldp_system_follows_user_1' AND CAST(wp_postmeta.meta_value AS CHAR) LIKE '%followed%' )\n) AND wp_posts.post_type = 'post' AND ((wp_posts.post_status = 'publish')) GROUP BY wp_posts.ID ORDER BY wp_posts.post_date DESC LIMIT 0, 10",

"request": "SELECT SQL_CALC_FOUND_ROWS  wp_posts.ID FROM wp_posts  INNER JOIN wp_postmeta ON ( wp_posts.ID = wp_postmeta.post_id ) WHERE 1=1  AND ( \n  ( wp_postmeta.meta_key = 'ldp_system_follows_user_1' AND CAST(wp_postmeta.meta_value AS CHAR) LIKE '%nofollowed%' )\n) AND wp_posts.post_type = 'post' AND ((wp_posts.post_status = 'publish')) GROUP BY wp_posts.ID ORDER BY wp_posts.post_date DESC LIMIT 0, 10",

Answer 1

To use the LIKE comparison, try a string:

$args = array(
    'post_type'     => 'post',
    'post_status'   => 'publish',
    'meta_query'    => array(
        array(
            'key'   => $user_key,
            'value' => 'followed', // String here
            'compare'   => 'LIKE',
        ),
    ),
);

return  get_posts($args);

Also, you can use WP_Query to help you debug:

$args = array(
    'post_type'     => 'post',
    'post_status'   => 'publish',
    'meta_query'    => array(
        array(
            'key'   => $user_key,
            'value' => 'followed', // String here
            'compare'   => 'LIKE',
        ),
    ),
);

$query = new WP_Query( $args );

echo '<xmp>';
print_r( $query->result ); 
die;

$query->result should contain the generated SQL, and will show you how WordPress is preparing your meta data.