Trying to get custom post meta through Jetpack JSON API

2 comments

1. From the documentation:

   According to the JetPack JSON API docs:

   By default, all metadata keys are allowed in the API, as long as they
   are not protected keys. Any metadata key that starts with _ is by
   default protected. Protected metadata keys can, however, be accessed
   and edited by users with the edit_post_meta (used for editing and
   viewing), add_post_meta and delete_post_meta capabilities as
   appropriate for each operation. We’ve also added a filter
   rest_api_allowed_public_metadata that allows you to specifically
   whitelist certain metadata keys to be accessed by any user, even if
   that key is protected.

   so the rest_api_allowed_public_metadata filter is what you are looking for.

   From the source code:

   If you check the JetPack’s source code, you will find this part:

       function is_metadata_public( $key ) {
               if ( empty( $key ) )
                       return false;
   
               // whitelist of post types that can be accessed
               if ( in_array( $key, apply_filters( 'rest_api_allowed_public_metadata', array() ) ) )
                       return true;
   
               return false;
       }
   

   in the file class.json-api-endpoints.php.

   You can also check out the allow_bbpress_public_metadata() function here to see how to implement this rest_api_allowed_public_metadata filter.

   Example:

   Here is a similar example for your case:

   /**
    * Whitelist protected meta keys
    *
    * @param array $allowed_meta_keys 
    * @return array $allowed_meta_keys 
    */
   function custom_rest_api_allowed_public_metadata( $allowed_meta_keys )
   {
       // only run for REST API requests
       if ( ! defined( 'REST_API_REQUEST' ) || ! REST_API_REQUEST )
           return $allowed_meta_keys;
   
       $allowed_meta_keys[] = '_ecmb_supporting_bands';
       $allowed_meta_keys[] = '_ecmb_tickets_avail';
       $allowed_meta_keys[] = '_ecmb_event_agelim';
   
       return $allowed_meta_keys;
   }
   
   add_filter( 'rest_api_allowed_public_metadata', 'custom_rest_api_allowed_public_metadata' );
   

   with the JSON output similar to this one:

   "metadata":[{"id":"196711","key":"_ecmb_event_agelim","value":"18"},
               {"id":"196709","key":"_ecmb_supporting_bands","value":"The Rolling Stones"}, 
               {"id":"196710","key":"_ecmb_tickets_avail","value":"5500"}]
   

2. In addition to @birgire reply, placing the filter code somewhere can be tricky:

   • If you place it under your theme’s “functions.php” file, a theme update could overwrite your code
   • Writing a plugin for just adding a filter is a lot of fuzz

   This is why what I did was to use the following plugin that allows you to write your custom actions and filters within WordPress admin panel without having to worry about losing it. http://wordpress.org/plugins/add-actions-and-filters/ .

   I had the same problem than you and after including the filter now it works like a charm.

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