How do I filter Child Posts by Parent Post ID for Custom Post types in WordPress REST API response?

I have two Custom post types: question and answer. “Questions” are hierarchical and they are parent posts for answers – which are child posts. For every answer, there’s a parent question. When someone asks a question, every answer given is correctly attributed to the same question. This has already been nicely done in the website. While I am building the APP, I can pull in all questions, but when it comes to answers, I can’t seem to filter out answer by parent question.

All questions can be obtained like this:

For answers, I am using custom endpoint with this code:

add_action( 'rest_api_init', 'custom_api_get_all_posts' );           function custom_api_get_all_posts() {        register_rest_route( 'app/v1', '/answers', array(          'methods' => 'GET',           'callback' => 'custom_api_get_all_posts_callback'     )); } function custom_api_get_all_posts_callback( $  request ) {  // Initialize the array that will receive the posts' data.      $  posts_data = array(); // Receive and set the page parameter from the $  request for pagination purposes $  paged = $  request->get_param( 'page' ); $  paged = ( isset( $  paged ) || ! ( empty( $  paged ) ) ) ? $  paged : 1;  // Get the posts using the 'post' and 'news' post types // $  avatar_url = get_avatar_url ( get_the_author_meta('ID'), $  size = '50' );  $  posts = get_posts( array(         'paged' => $  paged,                              'posts_per_page' => 10,            'post_type' => 'answer',      ) );  if ( is_array( $  filter ) && array_key_exists( 'question', $  filter ) ) {     $  args['post_parent_id'] = $  filter['question']; }  // Loop through the posts and push the desired data to the array we've initialized earlier in the form of an object foreach( $  posts as $  post ) {     $  id = $  post->ID;      $  posts_data[] = (object) array(          'id' => $  id,          'slug' => $  post->post_name,          'type' => $  post->post_type,         'title' => $  post->post_title,         'content' => $  post->post_content,         'question' => $  post->post_parent,     ); }                   return $  posts_data;                    


And by this, I can get all answers with their IDs, Answer Title, Content, and Parent Question Id in GET response at

QUESTION: How do I have to modify the code to be able to filter out specific answers based on question ID, something like: where 1234 is an ID for a parent question whose answers we need to display. All suggested filter plugins have failed to work, I’ve tried different forms of codes for so many hours, I really appreciate your help 🙂

Thanks! (Both question and answer are CPTs, and I am using WP Version – 4.9.8)

Knockout.js What is the correct way to reference $parent on js file?

I am new on Knockout.js, especially on how to use it in the Magento way.

I create a custom ViewModel with a js file called storepickup-select.js and an HTML template called storepickup-select.html.

I override Magento_Checkout/js/view/shipping on a custom shipping.js file on my custom module. In this file, I added two functions: selectedCarrierCode and saveStoreAddress.

When I call selectedCarrierCode on storepickup-select.html using the $ parent variable, it works fine and without any problem:

<form class="form form-shipping-storepickup" id="co-storepickup-form" data-bind="visible: $  parent.selectedCarrierCode()"> ... </form> 

But when I tried to call saveStoreAddress from storepickup-select.js, it throws me an error:

selectStore: function(){     ...                                 $  parent.saveStoreAddress(addresData);     ... } 

ReferenceError: $ parent is not defined

I tried some other options:

parent  this.parent this.$  parent 

But it doesn´t work. Why I can use $ parent on HTML file but I can´t use it on js file? And, what is the better way to call saveStoreAddress from js file?