Control character error, possibly incorrectly encoded - json

Question

I'm working on Mobile application with codenameone linked to symfony 4, user can participate to contest of videos i have this tables users,participation,video,concour everything is working very well but when i try to participate it brings me all the data correcty but it shows me this error: Control character error, possibly incorrectly encoded i hope that someone could help Me thank you.
This is my fonction on symfony4 :
*
*
* #Route("/api/competition/participate/", name="api_competitions_participate")
* #param Request $request
* #return Response
* #throws Exception
*/
public function participateAction(Request $request)
{
$r=$request->query->get('video');
$encoders = [new XmlEncoder(), new JsonEncoder()];
$normalizers = [new ObjectNormalizer()];
$serializer = new Serializer($normalizers, $encoders);
$video = $serializer->deserialize($r, Video::class, 'json');
$u=$this->getDoctrine()->getRepository(Users::class)->find($video->getOwner()['id']);
$video->setOwner($u);
$video->setPublishdate(new \DateTime('now'));
dump($video);
$r2=$request->query->get('participation');
$participation= $serializer->deserialize($r2, Participation::class, 'json');
$c=$this->getDoctrine()->getRepository(Concour::class)->find($participation->getConcour()['id']);
$participation->setUser($u);
$participation->setConcour($c);
$participation->setVideo($video);
$participation->setDateParticipation($video->getPublishdate());
dump($participation);
$em = $this->getDoctrine()->getManager();
$em->persist($video);
$em->persist($participation);
$em->flush();
dump($r);
return new JsonResponse();
}
and this is the function on codenameone
public void participate(Video v, Participation cp) {
Gson gson = new Gson();
String json = gson.toJson(v);
String json2 = gson.toJson(cp);
String url = Statics.BASE_URL + "/api/competition/participate/?video=" + json + "&participation=" + json2;
con.setUrl(url);
con.addResponseListener(new ActionListener<NetworkEvent>() {
#Override
public void actionPerformed(NetworkEvent evt) {
String str = new String(con.getResponseData());
System.out.println(str);
Dialog.show("Confirmation", "Your Video has been successfully added", "Ok", null);
con.removeResponseListener(this);
}
});
NetworkManager.getInstance().addToQueueAndWait(con);

Answer 1

I'm not familiar with Symfony so I'm not sure if this is the right answer. Also your approach of passing JSON in a get query is considered bad form by most. Normally JSON would be passed in the POST method body for REST calls.
To properly encode use this:
String url = Statics.BASE_URL + "/api/competition/participate/"
con.setUrl(url);
con.addArgument("video", json);
con.addArgument("participation", json2);
Also make sure the ConnectionRequest is constructed with false to indicate this is a GET operation and not POST.