dio put operation not working in fllutter - mongodb

Question

Im trying to connect flutter web app with mongodb using restheart api. PUT operation is required for creating new collection in mongoDB. I checked request in Postman, its works fine. I can get data from already existing collection (GET, POST works fine).
Code:
Dio dio = new Dio();
dio.interceptors.add(InterceptorsWrapper(onRequest:
(RequestOptions options) async {
var customHeaders = {
'content-type': 'application/json',
HttpHeaders.authorizationHeader: "Basic $encoded"
};
options.headers.addAll(customHeaders);
return options;
}));
String url = "http://localhost:8080/toofo";
response2 = await dio.put(url);
print("############## ${response2.statusCode} ##########");
print("############## ${response2.data} ##########");
Error:
Error: DioError [DioErrorType.RESPONSE]: XMLHttpRequest error.
at Object.throw_ [as throw] (http://localhost:52789/dart_sdk.js:4773:11)
at dio_for_browser.DioForBrowser.new.<anonymous> (http://localhost:52789/packages/dio/src/entry/dio_for_browser.dart.lib.js:359:27)
at Generator.next (<anonymous>)
at onValue (http://localhost:52789/dart_sdk.js:35655:33)
at _RootZone.runUnary (http://localhost:52789/dart_sdk.js:35540:58)
at _FutureListener.thenAwait.handleValue (http://localhost:52789/dart_sdk.js:30956:29)
at handleValueCallback (http://localhost:52789/dart_sdk.js:31466:49)
at Function._propagateToListeners (http://localhost:52789/dart_sdk.js:31498:17)
at _Future.new.[_completeWithValue] (http://localhost:52789/dart_sdk.js:31357:23)
at async._AsyncCallbackEntry.new.callback (http://localhost:52789/dart_sdk.js:31377:35)
at Object._microtaskLoop (http://localhost:52789/dart_sdk.js:35756:13)
at _startMicrotaskLoop (http://localhost:52789/dart_sdk.js:35762:13)
I also tried http package in flutter, got similar error.
This is the postman's status of PUT request 201Created

Answer 1

XMLHttpRequest error occurs for cross origin. Use this hearder
headers: {
'content-type': 'application/json',
"Access-Control-Allow-Origin": "*", // Required for CORS support to work
"Access-Control-Allow-Credentials": true, // Required for cookies, authorization headers with HTTPS
"Access-Control-Allow-Headers": "Origin,Content-Type,X-Amz-Date,Authorization,X-Api-Key,X-Amz-Security-Token,locale",
"Access-Control-Allow-Methods": "POST, OPTIONS"
},