Token Post Request With Flutter dart:io Invalid - http

Question

I'm doing a post request to an ASP.Net Web API to acquire a token. I am able to do this successfully with the dart HTTP package as follow:
Uri address = Uri.parse('https://myaddress:myport/token');
var response = await http.post(
address,
body: {
'username': 'MyUsername',
'password': 'MyPassword',
'grant_type': 'password'
},
).timeout(Duration(seconds: 20));
return response.body;
No problem with Postman either:
Now I want to do the same with the base dart:io class, as the testing server has a self signed certificate which I found the HTTP package has no bypass for (might be wrong), but for the life of me I cannot figure out where I am going wrong as when I debug the server the requests never get hit with the following code:
Uri address = Uri.parse('https://myaddress:myport/token');
HttpClient httpClient = HttpClient();
httpClient.connectionTimeout = Duration(seconds: 20);
httpClient.badCertificateCallback = ((X509Certificate cert, String host, int port) => true); // Allow self signed certificates
HttpClientRequest request = await httpClient.postUrl(address);
final Map<String, String> payLoad = {
'username': 'MyUsername',
'password': 'MyPassword',
'grant_type': 'password'
};
request.headers.contentType = new ContentType("application", "x-www-form-urlencoded", charset: "utf-8");
request.add(utf8.encode(json.encode(payLoad)));
// request.write(payLoad);
HttpClientResponse response = await request.close();
String responseBody = await response.transform(utf8.decoder).join();
httpClient.close();
responseBody is always:
"{"error":"unsupported_grant_type"}"
So I assume my encoding or structure is wrong, but with all possibilities I have tried, nothing works, any help would be appreciated.

Answer 1

i did the same but in my case i am requesting a soap web service, the bellow code do the job for me i hope it will for you
Future<XmlDocument> sendSoapRequest(String dataRequest) async {
final startTime = Stopwatch()..start();
_attemptsRequest = 0;
bool successful = false;
String dataResponse;
try {
Uri uri = Uri.parse('https://address:port/ADService');
var httpClient = HttpClient();
httpClient.connectionTimeout = Duration(milliseconds: 5000);
httpClient.idleTimeout = Duration(milliseconds: 5000);
httpClient.badCertificateCallback = ((X509Certificate cert, String host, int port) => true); // Allow self signed certificates
await httpClient
.openUrl('POST', uri)
.then((HttpClientRequest request) async {
request.headers.contentType =
new ContentType('application', 'text/xml', charset: 'UTF-8');
_attemptsRequest++;
request.write(dataRequest);
await request.close().then((HttpClientResponse response) async {
// var data = await response.transform(utf8.decoder).join();
// i didn't use this method cause it disorganize the response when there is high level of data, -i get binary data from the server-
var data = await utf8.decoder.bind(response).toList();
dataResponse = data.join();
successful = true;
httpClient.close();
});
_timeRequest = startTime.elapsed.inMilliseconds;
});
} catch (e) {
if (_attemptsRequest >= getAttempts) {
_timeRequest = startTime.elapsed.inMilliseconds;
if (e is SocketException)
throw Exception('Timeout exception, operation has expired: $e');
throw Exception('Error sending request: $e');
} else {
sleep(const Duration(milliseconds: 500));
}
}
try {
if (successful) {
XmlDocument doc;
doc = parse(dataResponse);
return doc;
} else {
return null;
}
} catch (e) {
throw Exception('Error converting response to Document: $e');
}
}