http - 如何使用 Dart 的 http 传递自定义对象列表？

Question

我正在尝试将自定义对象列表传递给我的 API。

下面是我的代码

import 'package:meta/meta.dart';
import 'package:json_annotation/json_annotation.dart';

part 'submit_survey_question_options_model.g.dart';

@JsonSerializable(nullable: false)
class SubmitSurveyQuestionOptionsModel {
  String questionId;
  String answer;

  SubmitSurveyQuestionOptionsModel(
      {@required this.questionId, @required this.answer});

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

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



Future<SubmitSurveyModel> submitSurvey(
      String userId,
      String facultyId,
      String surveyId,
      List<SubmitSurveyQuestionOptionsModel> submitSurveyQuestionOptionList,
      String subjectId) async {
    Map<String, dynamic> body = {
      "userId": userId,
      "facultyId": facultyId,
      "surveyId": surveyId,
      "survey": submitSurveyQuestionOptionList,
      "subjectId": subjectId
    };

    final response = await http.post(
      SUBMIT_SURVEY_URL,
      body: json.encode(body),
    );

    SubmitSurveyModel submitSurveyModel = standardSerializers.deserializeWith(
        SubmitSurveyModel.serializer, json.decode(response.body));


    return submitSurveyModel;
  }

我在我的 pubspec 中使用 json_serializable。我使用 flutter packages pub run build_runner build

构建了可序列化类

由于数据未正确提交，我无法弄清楚是什么问题？

我已经引用了以下链接，但无法正常工作

Flutter Error: type 'AddressInfo' is not a subtype of type 'String' in type cast

Dart Error Converting Object To JSON

Answer 1

尝试传递以下 header

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

  final response = await http.post(Uri.encodeFull(url), body: json.encode(body), headers: headers);