ImplyContentTypeInterceptor does not set content type to json when data is Json Array

[MrKnos]

Package

dio

Version

^5.0.2

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Dart Version

Dart SDK version: 2.19.2 (stable) (Tue Feb 7 18:37:17 2023 +0000) on "macos_x64"

Steps to Reproduce

1. Send request data as Json Array.

import 'package:dio/dio.dart';
import 'package:dio/io.dart';
import 'package:dio_imply_content_type_flutter/book_entity.dart';
import 'package:flutter/material.dart';

Future<void> main() async {
  await createBooks();
  runApp(const MyApp());
}

Future<void> createBooks() async {
  Dio client = Dio(BaseOptions(baseUrl: 'http://localhost:8081'));
  client = _setupProxy(client: client);

  const book1 = BookEntity(title: 'Book 1', authorName: 'John doe');
  const book2 = BookEntity(title: 'Book 2', authorName: 'Jane doe');

  await client.post('/books/create', data: [book1.toJson(), book2.toJson()]);
}

Dio _setupProxy({
  required Dio client,
}) {
  client.httpClientAdapter = IOHttpClientAdapter()
    ..onHttpClientCreate = (client) {
      return client..findProxy = (uri) => 'PROXY 192.168.20.60:9090';
    };

  return client;
}

BookEntity.dart

import 'package:json_annotation/json_annotation.dart';

part 'book_entity.g.dart';

@JsonSerializable()
class BookEntity {
  const BookEntity({
    required this.title,
    required this.authorName,
  });

  factory BookEntity.fromJson(
    Map<String, dynamic> json,
  ) =>
      _$BookEntityFromJson(json);

  Map<String, dynamic> toJson() => _$BookEntityToJson(this);

  final String title;

  @JsonKey(name: 'author_name')
  final String authorName;
}

Expected Result

ImplyContentTypeInterceptor should attach content-type json to request header when content type is Json Array.

Actual Result

No content-type header exist and get warning.

[🔔 Dio] List<Map<String, dynamic>> cannot be usedto imply a default content-type, please set a proper content-type in the request.
         #0      ImplyContentTypeInterceptor.onRequest (package:dio/src/interceptors/imply_content_type.dart:45:36)
         #1      DioMixin.fetch.requestInterceptorWrapper.<anonymous closure>.<anonymous closure> (package:dio/src/dio_mixin.dart:412:26)
         #2      new Future.<anonymous closure> (dart:async/future.dart:253:37)
         #3      Timer._createTimer.<anonymous closure> (dart:async-patch/timer_patch.dart:18:15)
         #4      _Timer._runTimers (dart:isolate-patch/timer_impl.dart:398:19)
         #5      _Timer._handleMessage (dart:isolate-patch/timer_impl.dart:429:5)
         #6      _RawReceivePort._handleMessage (dart:isolate-patch/isolate_patch.dart:192:26)

Proxy log (content-type not exist)

[AceChen1]

@AlexV525, looks like my application also meet this case issue on dio 5.2.0 version, but my case is List<String> not List<Map>, will your guys will do List<String> handling ? BTW, have any best way to solve those issue? i think add field type handling is not the final solution, as the type have more and more.

[AlexV525]

but my case is List, not List

?

[AceChen1]

but my case is List, not List

?

looks like my application also meet this case issue on dio 5.2.0 version, but my case is List<String> not List<Map>, will your guys will do List<String> handling ? BTW, have any best way to solve those issue? i think add field type handling is not the final solution, as the type have more and more.