WordPress REST API - Modify JSON before importing

Question

Hi guys so I have some data hitting my WP from an external company at /wp-json/wp/v2/jobs/ to be imported as a post.

This data contains JSON that needs to be imported, however it tried to set taxonomies using strings e.g. "Manager" rather than the term_id which would be say "381". This means I get an error returned.

{
    "code": "rest_invalid_param",
    "message": "Invalid parameter(s): job_location, job_industry, job_sector",
    "data": {
        "status": 400,
        "params": {
            "job_location": "job_location[0] is not of type integer.",
            "job_industry": "job_industry[0] is not of type integer.",
            "job_sector": "job_sector[0] is not of type integer."
        }
    }
}

So what I want is when they post this value to us, for example:

"job_sector":"Manager"

I want to instead loop through our taxonomies, and find the ID for this "Manager" job_sector, rebuild the JSON and THEN have WP import the data I pass, error free with the proper ID.

Can anyone help on how I can intercept the JSON and pass it along in the proper format?

I tried "rest_pre_dispatch" but this seems to be only editing the result sent back to them, it has already been processed by WP.

EDIT: Here is my code:

 function wpse281916_rest_check_referer( $result, $server, $request ) {
     if ( null !== $result ) {
         // Core starts with a null value.
         // If it is no longer null, another callback has claimed this request.
         // Up to you how to handle - for this example we will just return early.
         return $result;
     }

     $array = json_decode($result, true);
     $term = get_term_by('name',$array["job_sector"],'job_sector');
     $term = json_decode(json_encode($term),true);
     $termid = $term['term_id'];   
     $array['job_sector'] = $termid;
     $result = json_encode($array);
     return $result;
 }

// add the filter
add_filter( 'rest_pre_dispatch', 'wpse281916_rest_check_referer', 10, 3 );

EDIT2: After suggestion

    function wpse281916_rest_check_referer( $result, $server, $request ) {
        if ( null !== $result ) {
            // Core starts with a null value.
            // If it is no longer null, another callback has claimed this request.
            // Up to you how to handle - for this example we will just return early.
            return $result;
        }

        $array = json_decode($request, true);
        $term = get_term_by('name',$array["job_sector"],'job_sector');
        $term = json_decode(json_encode($term),true);
        $termid = $term['term_id'];
        $array['job_sector'] = $termid;
        $request = json_encode($array);
        return null;
    }

   // add the filter
   add_filter( 'rest_pre_dispatch', 'wpse281916_rest_check_referer', 10, 3 );

Answer 1

Using the rest_pre_dispatch hook is probably the most straightforward way to go, but you need to be careful about putting your new request data back into the WP_REST_Request object properly.

You were reassigning the WP_REST_Request object to an array of request data. Those changes are not persisted because the parameter is not passed by reference. Instead, you want to modify the WP_REST_Request object.

You can assign a parameter to the request object using array like syntax, or by using WP_REST_Request::set_param( $param_name, $param_value ).

You should also check to make sure you are only running this code on the correct route. I'd also move the priority to fire the hook earlier since you essentially are saying that this change should apply to everything happening on this request.

function wpse281916_rest_check_referer( $result, $server, $request ) {

    if ( '/wp/v2/jobs' !== $request->get_route() || 'POST' !== $request->get_method()) {
        return $result;
    }

    $job_sector = $request['job_sector'];

    if ( null === $job_sector ) {
        return $result;
    }

    $term = get_term_by( 'name', $job_sector, 'job_sector' );

    if ( $term && ! is_wp_error( $term ) ) {
        $request['job_sector'] = $term->term_id;
    } else {
        $request['job_sector'] = 0;
    }

    return $result;
}

// add the filter
add_filter( 'rest_pre_dispatch', 'wpse281916_rest_check_referer', 0, 3 );

Answer 2

Seems like you looking for the rest_pre_dispatch hook.

This hook allows hijacking the request before dispatching by returning a non-empty. The returned value will be used to serve the request instead.

From the docs:

$result

(mixed) Response to replace the requested version with. Can be anything a normal endpoint can return, or null to not hijack the request.

Seems like to you have to modify the $request and return null in order to no hijack the default response.