How to send POST request from Flutter app to PHP server

I’ve tried to send a POST request from my Dart application to a PHP file on my server that only checks if $_POST[‘username’] is set, what happens is that the request seems to reach the server but the server refuses to “read it”:

This is what the server sees when a request is received (seen by using: file_get_contents(‘php://input’))

{"username":"testUsername"}

but if I try to do something like:

isset($_POST['username']) 

this always returns false.

Here is the method I use to send the POST request:

  import 'dart:convert';
  import 'package:http/http.dart' as http;

  final String url = "my.domain.com";
  final String unencodedPath = "/subfolder/myfile.php";
  final Map<String, String> headers = {'Content-Type': 'application/json; charset=UTF-8'};
  final Map<String,String> body = {'username': 'testUsername'};
    
    Future<http.Response> makePostRequest(String url, String unencodedPath , Map<String, String> header, Map<String,String> requestBody) async {
      final response = await http.post(
        Uri.http(url,unencodedPath),
        headers: header,
        body: jsonEncode(requestBody),
      );
      print(response.statusCode);
      print(response.body);
    }

    makePostRequest(url, unencodedPath, headers, body);

why does isset($_POST[‘username’]) not see my POST sent value?

Answer

Your post request from flutter side is correct

isset($_POST['username']) 

will return null as username is part of the json object, It would have worked if :

username = {"username":"testUsername"}

your request satisfied the above format.

To check for data you can do is :

 if(!isset($_POST)){
        // Takes raw data from the request
        $json = file_get_contents('php://input');

// Converts it into a PHP object
        $data = json_decode($json);
      //add your check here that is $data["username"] as bellow
        isset($data["username"])
    }

You can also check for valid json using other methods.