Flutter http Maintain PHP session

HTTP is a stateless protocol, so servers need some way to identify clients on the second, third and subsequent requests they make to the server. In your case you might authenticate using the first request, so you want the server to remember you on subsequent requests, so that it knows you are already authenticated. A common way to do this is with cookies.

Igniter sends a cookie with the session id. You need to gather this from each response and send it back in the next request. (Servers sometimes change the session id (to reduce things like clickjacking that we don’t need to consider yet), so you need to keep extracting the cookie from every response.)

The cookie arrives as an HTTP response header called set-cookie (there may be more than one, though hopefully not for simplicity). To send the cookie back you add a HTTP request header to your subsequent requests called cookie, copying across some of the information you extracted from the set-cookie header.

Hopefully, Igniter only sends one set-cookie header, but for debugging purposes you may find it useful to print them all by using response.headers.forEach((a, b) => print('$a: $b'));. You should find Set-Cookie: somename=abcdef; optional stuff. We need to extract the string up to, but excluding the ;, i.e. somename=abcdef

On the next, and subsequent requests, add a request header to your next request of {'Cookie': 'somename=abcdef'}, by changing your post command to:

http.post(url, body: data, headers:{'Cookie': cookie})

Incidentally, I think you have a mismatch of awaits and thens in your code above. Generally, you don’t want statics in classes, if they should be top level functions instead. Instead you could create a cookie aware class like:

class Session {
  Map<String, String> headers = {};

  Future<Map> get(String url) async {
    http.Response response = await http.get(url, headers: headers);
    updateCookie(response);
    return json.decode(response.body);
  }

  Future<Map> post(String url, dynamic data) async {
    http.Response response = await http.post(url, body: data, headers: headers);
    updateCookie(response);
    return json.decode(response.body);
  }

  void updateCookie(http.Response response) {
    String rawCookie = response.headers['set-cookie'];
    if (rawCookie != null) {
      int index = rawCookie.indexOf(';');
      headers['cookie'] =
          (index == -1) ? rawCookie : rawCookie.substring(0, index);
    }
  }
}