Difficulty in receiving POST parameter in symfony using angular 4 - php

Question

I am using symfony with angular 4. Both are different projects. In symfony I am returning a post variable which is sent via angular. I am just returning the value. Nothing other than that.
But it's returning me blank value. But when I am testing that symfony url using postman it's returning the correct value.
Symfony code
header('Access-Control-Allow-Origin: *');
header('Access-Control-Allow-Methods: GET, POST');
header('Access-Control-Allow-Headers:Content-Type,Accept');
return new Response("a-".$request->request->get('roll')."-b"); //gives '**a- -b**' in console. but from postman gives `a-2-b`
Angular code
this.http.post("http://localhost:8000/user/login",{roll:2}).subscribe(
(data) => console.log(data)
);

Answer 1

Your postman's POST request is different than the Angular's POST request
Maybe in Angular you have to add the content-type: application/json header.
To debugging I advice you to compare the two request with logging in symfony code

Answer 2

I'm not 100% sure but I believe you have to JSON.stringify your object on the angular side:
this.http.post("http://localhost:8000/user/login",JSON.stringify({roll:2})).subscribe(
(data) => console.log(data)
);
Next, as said in comments above. Symfony handles x-www-form-urlencoded body by default. For JSON requests you will need to parse it yourself.
e.g.:
$data = json_decode($request->getContent(), true));
Now doing this in every controller action may seem tedious and you'll loose the Symfony Parameter bag.
You can solve this by making a Request listener:
e.g.:
class JsonRequestEventListener
{
public function onKernelRequest(GetResponseEvent $event)
{
$request = $event->getRequest();
if (empty($request->getContent()))
{
return;
}
if (!$this->isJsonRequest($request))
{
return;
}
if (!$this->transformJsonBody($request))
{
$response = Response::create('Unable to parse request.', 400);
$event->setResponse($response);
}
}
private function isJsonRequest(Request $request)
{
return 'json' === $request->getContentType();
}
private function transformJsonBody(Request $request)
{
$content = $request->getContent();
if ($content === '')
{
return true;
}
$data = json_decode($content, true);
if (json_last_error() !== JSON_ERROR_NONE)
{
return false;
}
if ($data === null)
{
return true;
}
$request->request->replace($data);
return true;
}
}
What this listener does is the following:
When a request comes in, it checks if there is any content and if the request is json. Then it tries to json_decode the request and inserts it in the request parameter bag. ($request->request ...)
The next thing you will have to do is register this listener:
e.g.:
jsonrequest.listener:
class: AppBundle\EventListener\JsonRequestEventListener
tags:
- { name: kernel.event_listener, event: kernel.request, method: onKernelRequest, priority: 100 }
And from now on, if your request is of type application/json and it contains valid json, you can find it's values in the Request Parameter bag:
public function someAction(Request $request)
{
$request->request->all() //holds the json
}
As I can see from your sample, you set the CORS headers in your controller as well. You could in the same way write a CORS listener to handle this for you.