[dio] Some map response returns null but using Postman can see the field with the correct result

[fakhravari]

Package

dio

Version

5.1.2

Output of flutter doctor -v

No response

Dart Version

No response

Steps to Reproduce

1

Expected Result

I test with package http, it shows responce in the output, but it is null in the output dio.

Recording.2023-07-10.150840.mp4

Actual Result

UserName:3501578873
Password:12345
IdLanguage:1

https://mobiletest.pmlm.ir/pisc/v3/LoginCustomer

[AlexV525]

I can reproduce this using the below code:

import 'package:dio/dio.dart';
import 'package:test/test.dart';

void main() {
  test('request something', () async {
    final response = await Dio().post(
      'https://mobiletest.pmlm.ir/pisc/v3/LoginCustomer',
      data: {'UserName': '3501578873', 'Password': '12345', 'IdLanguage ': 1},
    );
    print(response);
  });
}

[fakhravari]

import 'dart:convert';
import 'package:flutter_test/flutter_test.dart';
import 'package:dio/dio.dart';
import 'package:http/http.dart' as http;

void main() {
  test('request Dio', () async {
    final response = await Dio().post(
      'https://mobiletest.pmlm.ir/pisc/v3/LoginCustomer',
      data: {'UserName': '3501578873', 'Password': '12345', 'IdLanguage ': 1},
    );
    print(response);
  });

  test('request Http', () async {
    var url = Uri.parse('https://mobiletest.pmlm.ir/pisc/v3/LoginCustomer');
    var response = await http.post(
      url,
      headers: {'Content-Type': 'application/x-www-form-urlencoded'},
      body: jsonEncode(
          {'UserName': '3501578873', 'Password': '12345', 'IdLanguage ': 1}),
    );

    print(response.body);
  });
}

Recording.2023-07-15.094215.mp4

[AlexV525]

After debugging what's happened to your requests, the dio request is different compared to the http.

For http request:

• The body will be encoded as UTF-8 bytes in the HttpClientRequest, corresponding length: 60.
• The body will be sent exactly as an application/x-www-form-urlencoded content as defined.
• The response returns 1562 bytes, with user: null and Authorization: null.
• The return AnbarName is پست which corresponds to bytes [217, 190, 216, 179, 216, 170].
• The response bytes are decoded correctly by the decoder.

For dio and Postman request:

• The body will be implied as JSON content in the ImplyContentTypeInterceptor because it's a Map, also with application/json as the content-type.
• The response returns 2588 bytes, with all fields non-null.

To make both requests the same, since user: null and Authorization: null seems abnormal or invalid, I suggest:

• Do not use jsonEncode for http request, which corrects the usage of the http request.
• Set Options(contentType: Headers.formUrlEncodedContentType) when using the dio request.

Closing as invalid usages.