强制执行json中间件

Hey guys so i'm making a restful api and i decided to make a middleware that always sets the header as content-type application/json however the problem is that it never does that.. when i send the request in postman it still says the content-type is text/html despite the middleware.. to be clearer here is my middleware :

class EnforceJSON
{
    public function handle($request, Closure $next)
    {
    $response = $next($request);

    $response->headers->set('Content-Type', 'application/json');

    return $response;
    }

}

and even after setting the middleware in web.php for the routes i still get this in postman

You do not need to set Content-Type: applicaton/json header from a middleware. Laravel will set it for you if you send a json response.

If can use this function

return response()->json($response_data, 200);

EDIT:

My guess is this is what you are looking for

class JsonHeader
{
    public function handle($request, Closure $next)
    {
        $acceptHeader = $request->header('Accept');
        if ($acceptHeader != 'application/json') {
            return response()->json([], 400);
        }

        return $next($request);
    }
}

Got it from accepted answer of this question How to set header for all requests in route group

Postman will show the headers that you send, not the headers after your middleware has modified them. The middleware operates on a request after it is received ...

If you want to check your middleware is working, try dumping the request headers from the controller that receives the request:

return ($request->header());