Header already sent

[agreatfool]

  app.get('/oauth2next', (HttpContext ctx) {
    Map queries = Uri.splitQueryString(ctx.uri.query);
    Map done = pinGoogleOAuth.processOAuthNext(queries).then((Map done) {
      if (done['result']) {
        ctx.res.redirect(Uri.parse(ctx.uri.host)); // FAILED on this line
      } else {
        ctx.sendJson(done);
      }
    });
  });

Uncaught Error: Bad state: Header already sent
Stack Trace:
#0      _HttpResponse.redirect (dart:io/http_impl.dart:530)
#1      main.<anonymous closure>.<anonymous closure> (file:///.../bin/web.dart:68:25)
#2      _rootRunUnary (dart:async/zone.dart:730)
#3      _RootZone.runUnary (dart:async/zone.dart:864)
#4      _Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:488)
#5      _Future._propagateToListeners (dart:async/future_impl.dart:571)
#6      _Future._completeWithValue (dart:async/future_impl.dart:331)
#7      _Future._asyncComplete.<anonymous closure> (dart:async/future_impl.dart:393)
#8      _asyncRunCallbackLoop (dart:async/schedule_microtask.dart:23)
#9      _asyncRunCallback (dart:async/schedule_microtask.dart:32)
#10     _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:128)

Any idea when the headers were sent and by who?

[SamVerschueren]

Did you use pub to install Express or did you download the sourcecode of github? If I find the time I will have a look at the problem...

The querystring parameters can also be found in ctx.params by the way ;).

[agreatfool]

Yes, Express was installed before I ran the code.

And thank you for the hint, I found it~

  Map<String,String> get params{
    if (_params == null){
      _params = pathMatcher(routePath, req.uri.path);
      _params.addAll(req.uri.queryParameters);
    }
    return _params;
  }

[SamVerschueren]

What library are you using for the OAuth? Can you give a little bit more code as well. I am trying to reproduce the error.

[agreatfool]

Sorry for the late reply. I'm using the official oauth2 lib on pub site: https://pub.dartlang.org/packages/oauth2 You can have a look at my codes in repo: https://github.com/agreatfool/Cart Entrance is: src/bin/web.dart

Workflow is: First, send oauth privileges confirm request

app.get('/oauth2', (HttpContext ctx) {
  ctx.res.redirect(Uri.parse(pinGoogleOAuth.getOAuthUrl())); // redirect user from my site to google oauth page
});

Second, user confirm the oauth dialogue, and redirected to my site '/oauth2next'

app.get('/oauth2next', (HttpContext ctx) {
  Map queries = Uri.splitQueryString(ctx.uri.query);
  Map done = pinGoogleOAuth.processOAuthNext(queries).then((Map done) {
    if (done['result']) {
      ctx.res.redirect(Uri.parse(ctx.uri.host)); // FAILED on this line
    } else {
      ctx.sendJson(done);
    }
  });
});

Third, the logic in function pinGoogleOAuth.processOAuthNext:

  Future<Map> processOAuthNext(Map data) {
    var completer = new Completer();

    Map res = {
      'result': false,
      'message': ''
    };

    PinLogger.instance.fine('[PinGoogleOAuth] processOAuthNext data: ${JSON.encode(data)}');

    if (data.containsKey('code')) {
      // oauth code got, process next step
      LibHttp.post(
          GOOGLE_OAUTH_TOKEN_URL,
          body: {
              'code': data['code'],
              'client_id': _identifier,
              'client_secret': _secret,
              'redirect_uri': _redirectUrl,
              'grant_type': 'authorization_code'
          }
      ).then((LibHttp.Response response) {
        // token response got
        PinLogger.instance.fine('[PinGoogleOAuth] processOAuthNext auth response: ${response.body}');
        Map authResponse;
        try {
          authResponse = JSON.decode(response.body);
        } catch (e) {
          res['message'] = response.body;
          completer.complete(res);
        }
        if (authResponse.containsKey('access_token')) {
          // access token got
          var expiration = null;
          if (authResponse.containsKey('expires_in')) {
            var now = new DateTime.now();
            now.add(new Duration(seconds: authResponse['expires_in']));
            expiration = now.millisecondsSinceEpoch;
          }
          Map credentials = {
              'accessToken': authResponse['access_token'],
              'refreshToken': authResponse['refresh_token'],
              'tokenEndpoint': GOOGLE_OAUTH_TOKEN_URL,
              'scopes': _scopes,
              'expiration': expiration
          };
          if (authResponse.containsKey('id_token')) {
            credentials['idToken'] = authResponse['id_token'];
          }
          var decoder = new JsonEncoder.withIndent('    ');
          new File(_credentialsFilePath).writeAsString(decoder.convert(credentials)).then((_) {
            res['result'] = true;
            completer.complete(res);
          });
        } else if (authResponse.containsKey('error')) {
          // error
          res['message'] = 'Error: ${authResponse['error']}';
          completer.complete(res);
        } else {
          // unrecognized
          res['message'] = 'Error: Unrecognized oauth response';
          completer.complete(res);
        }
      });
    } else if (data.containsKey('error')) {
      // error
      res['message'] = 'Error: ${data['error']}';
      completer.complete(res);
    } else {
      // unrecognized
      res['message'] = 'Error: Unrecognized oauth response';
      completer.complete(res);
    }

    return completer.future;
  }

[DisDis]

Express don't work after update dart to 1.6. All request broken "Header already sent"

[vvnab]

    Express don't work after update dart to 1.6. All request broken "Header already sent"

Dart v1.9.1 All request broken "Header already sent"