how to get post meta where value is an array of key value pairs

Question

I am trying to get the post meta with meta query where value is an array of key value pairs.

 $user_id = '123';

  $arr = array();

  $arr['a'] => "somevalaaa" ;
  $arr['user_id'] => $user_id ;
  $arr['c'] => "somevalyyy" ;

Adding post meta

  add_post_meta($review_post_id, 'key_of_post_meta', $arr );

Getting post meta (having user id same as $user_id) with meta query, where I am wrong ?

  $args = array(
     'post_type' => 'as_reviews',
     'posts_per_page' => -1,
     'post_status' => 'publish',
          'meta_query' => array(
              array(
                'key' => 'key_of_post_meta',
                'value' => array('user_id'=>$user_id),
                'compare' => 'IN',
               ),
            ),
       );



  $query = new WP_Query($args);

Answer 1

The meta_query cannot be used to search value which are stored as serialized arrays. You can use it to search multiple values (meta-fields can have several values using the same key).

You need a different approach to solve your problem, this is what I suggest,

store your meta field with the user id as part of the key name,

add_post_meta($review_post_id, 'key_of_post_meta_'.$user_id, $arr );

next, retrieve your posts with,

$args = array(
     'post_type' => 'as_reviews',
     'posts_per_page' => -1,
     'post_status' => 'publish',
     'meta_key' => 'key_of_post_meta_'.$user_id
    );
  $query = new WP_Query($args);