rwmb_after_save_post

Hi Max,

I think the problem is there are multiple meta boxes and the hooks don't fire properly. They fire per meta box, so if there are 2 meta boxes, the hook rwmb_before_save_post might fire before one meta box saving action, but after another meta box saving action.

As Meta Box uses hook save_post_{$post_type} with priority to save the data, please try the replacing the hooks with:

add_action('save_post_{your_post_type}', 'api_get_old_fields', 0);
add_action('save_post_{your_post_type}', 'api_set_new_fields', 20);

Yes, I think so. Not sure where it comes from, since Meta Box doesn't use JSON at all.

Both rwmb_* functions and WordPress's get_post_meta() don't use JSON at all. They use serialize for arrays. Maybe you need to check how data is saved in your case, just to make sure it's valid. Anyway, as the data is there, you can use json_decode function to decode it.

You're data is a plain array encoded in JSON, so $value[$i] is correct to iterate each of the value stored.

I'm not sure how it's saved in the DB, though. But at least it works for now. Please post the code for the meta box/field here for me to see why it saves as json-array.

Hmm, couldn't find anywhere the JSON value is stored.

However, I found something confusing in your code:

This part:

if( is_string($field['value']) && is_array(json_decode($field['value'], true)) ) {
        $array = json_decode( $field['value'] );
        $i = 0;
        foreach( $array as $value) {
          update_post_meta($post_id, '_property_' . $new_level . '_' . $field['key'], $value[$i]);
          $i++;
        }
      } else {...}

Here you check if $field['value'] is a json-string. But when you decode it with $array = json_decode( $field['value'] );, then $array will be an object! Not sure why the next foreach loop work.