Retriving all users with REST API not working

Question

At the moment I'm using Postman to hit the endpoints and I have a successful Basic Authentication but so far I'm unable to get all the registered users. My request:

https://example.com/wp-json/wp/v2/users

returns only users that have posts even though I have inserted:

add_filter( 'rest_user_query' , 'custom_rest_user_query' );
function custom_rest_user_query( $prepared_args, $request = null ) {
  unset($prepared_args['has_published_posts']);

  return $prepared_args;
}

in my functions file. I have also tried applying a filter:

https://example.com/wp-json/wp/v2/users?filter[per_page]=0

But I still get the same result: Only users with posts. I have been banging my head on for days now...

Answer 1

The problem may be pagination

The API only returns 10 results per page, and needs follow up requests to fetch the rest. WP includes a HTTP header that tells you how many total results and the number of pages. It has a hard limit of 100 per page maximum, if you request 200, you will be capped to 100.

So your missing users may be on page 2 or 3 etc

I strongly recommend reading the REST API handbook on the official developer site, here is the page detailing pagination:

https://developer.wordpress.org/rest-api/using-the-rest-api/pagination/

Answer 2

WP has nice build in tools to work with db, my suggestion would be to register your endpoint and use for a callback function something like this:

function getAllUsers(){
    global $wpdb;
    $query = $wpdb->get_results( " SELECT `ID` FROM `wp_users` " , OBJECT);
    $ids = array();
    foreach($query as $id){
        array_push($ids, $id->ID);
    }
    return $ids;    
}

It will return all the ID's. Then you can use get_post_meta to gather meta info about the user. Of course consider protecting your endpoint since it hands over user information.