How to return new field from cakephp beforeMarshal -

so have rest api expecting json string containing field, eg, 'status'. need relate string id , have obtained id using beforemarshal in table model:

$query = $status->find()         ->where (['status' => 'new']);      $id = $query->first();     $data['status_id'] .= $id->id;

problem above, $data['status_id'] not work because 'status_id' not in incoming fields.

how can add 'status_id' $data field, or return beforemarshal, such replaces 'status' string value ?

ie, incoming: {"status": "new"}, before saving entity, need {"status_id": "2"}

this cakephp v3

Core code