WP Query | search by sub-categories

I have a small problem with the functioning of a search bar that gives the user the possibility to find professionals based on their job categories.

I explain: I am talking about a portal that allows the user to be able to carry out a search as written above.

How I managed the programming: if it is a portal where there are professionals, I created the custom post type: Pro

To specify the services that these professionals are able to perform, I created a plugin that allows me by specifying in the array which custom post types to grant the possibility to implement taxonomies:

register_taxonomy( 'categoria', array( 'pro' ), $  args ); 

now very simply I have implemented a form on a page:

<div id="search_video"  class="container-fluid">     <div style="text-align: center;background-color: #fff;" class="col-md-12">         <form name="NOME_FORM" method="get" id="advanced-searchform" role="search" action="<?php echo esc_url( home_url( '/results' ) ); ?>">             <div class="input-group mb-3">                 <div class="input-group-prepend">                     <span class="input-group-text"><i class="fa fa-search"></i></span>                 </div>                 <input type="text" id="art" name="art" class="form-control">             </div>         </form>     </div>     </div> </div> 

pointing to the results page.

to display the results I used this query:

<?php $  art_p = $  _GET['art'];         $  query_v = array(             'post_type' => array('pro'),             'posts_per_page'    => -1,             'orderby' => 'meta_value',             'order' => 'ASC',             'tax_query' => array(                 array(                     'taxonomy' => 'categoria',                     'terms' => $  art_p,                 )             )         );         $  res_v = new WP_Query( $  query_v );         ?> 

now the problem:

I have implemented two test professional profiles, in the services category, I have specified as a sub-category of services for professional A:

  • creation of websites

and for professional B:

  • logo creation

but if I look in the website creation bar: it gives me both professionals as a result and this is not good.

So my question is how can I filter the results so that the user search is based on the sub-category of services and only brings out the professionals who own that sub-category, what did I do wrong with my query?