title: Return JSON NULL
body: <p>I have a data encoding problem. My database has accents in one of the columns, in the api return that column in a PDO query SQL SERVER in php. As soon as I return I transform into JSON by the json_encode method, plus the JSON comes NULL. When I give var_dump the question letters with accents this appears '�' and in json empty.
  I know it's the encoding I need to convert to UTF8 but I'm not able to do this conversion in php. Can anyone help me?</p>
  
  <p><img src="https://i.stack.imgur.com/aaEgb.png" alt="enter image description here"></p>