Invalid Header Name In Flutter HTTP Request

Question

I have a login page where i am trying to send a login request to my backend. But I get an Unhandled Exception: Invalid header field name. Here is my submit function

submit() async {
var res = await LoginAPI().loginData(
    {'email': _emailController.value, 'password': _passwordController.value});
var body = json.decode(res.body);
print(body);
}

Then in my LoginAPI class here is my loginData function that makes the call to the backend

import 'dart:convert';

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

class LoginAPI {
  final String _url = "http://10.0.2.2:8000/api/";
  Map<String, String> headers = {"Content-type": "application/json"};

 loginData(data) async {
 var fullUrl = _url + "v1/users/login";
  return await http.post(
    fullUrl, 
    body: jsonEncode(data),
    headers: headers
    );      
   }
  }

Here is my request through postman

Here is my response through postman

When I make the same request with Postman i get the response I am supposed to get. What Am i doing wrong?

I have shared my response and that post did not help me at all. — Patrick Obafemi
– Patrick Obafemi, Commented Nov 28, 2019 at 9:21
You may be encountering a well known server bug, where the server expects a certain case of the header names. package:http lower cases all header names, which is perfectly valid but confuses some servers. Confirm with another client (not sure if you can control the header name in postman) with a lower case content-type. If you can duplicate the problem, then it's a server issue. You can always just use Dart's HttpClient which does not change the case of headers. — Richard Heap
– Richard Heap, Commented Nov 28, 2019 at 15:02
@RichardHeap thanks. So i sent a request with postman using lower case content-type and I got the right response back. I guess I will just use dart HttpCLient — Patrick Obafemi
– Patrick Obafemi, Commented Nov 29, 2019 at 8:09

Jay Gadariya · Accepted Answer · 2019-11-28 09:47:12Z

1

try this

Map<String, String> headers = {"Content-type": "application/json",  "Accept": "application/json",};

answered Nov 28, 2019 at 9:47

Jay Gadariya

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Richard Heap · Accepted Answer · 2019-11-29 23:15:51Z

1

It looks from your postman request that you are just sending form data (not a json encoded body). package:http will form encode the body for you (and add the content type header) if you do the following:

  return await http.post(
    fullUrl, 
    body: data,
  );

answered Nov 29, 2019 at 23:15

Richard Heap

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Patrick Obafemi · Accepted Answer · 2019-12-03 13:20:32Z

0

So i was able to solve the issue. The issue was with my CORS middleware on my server. I just made some changes and it worked fine. So if anyone has this issue just know it has nothing to do with flutter but most probably CORS

answered Dec 3, 2019 at 13:20

Patrick Obafemi

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