Flutter 错误：参数类型“动态”不能分配给参数类型“Iterable<dynamic>”

Question

请提供帮助。 我正在尝试使用 JSON to Dart 工具创建模型https://app.quicktype.io/

目的是从 JSON API 中检索所有公司（及其属性）的列表。

我收到以下错误：

• 参数类型“动态”不能分配给参数类型 Map
• 参数类型“动态”不能分配给参数类型 Iterable
• 参数类型“动态”不能分配给参数类型 Int

请参考下图。 the argument type 'dynamic' can't be assigned to the parameter type...

谢谢。

Answer 1

我已经测试过这个类，它可以正常工作

import 'dart:convert';

CompanyModel companyModelFromJson(String str) => CompanyModel.fromJson(json.decode(str));

String companyModelToJson(CompanyModel data) => json.encode(data.toJson());

class CompanyModel {
    CompanyModel({
        this.companies,
    });

    List<Company> companies;

    factory CompanyModel.fromJson(Map<String, dynamic> json) => CompanyModel(
        companies: List<Company>.from(json["companies"].map((x) => Company.fromJson(x))),
    );

    Map<String, dynamic> toJson() => {
        "companies": List<dynamic>.from(companies.map((x) => x.toJson())),
    };
}

class Company {
    Company({
        this.id,
        this.name,
    });

    int id;
    String name;

    factory Company.fromJson(Map<String, dynamic> json) => Company(
        id: json["id"],
        name: json["name"],
    );

    Map<String, dynamic> toJson() => {
        "id": id,
        "name": name,
    };
}

作为替代方案，您可以使用来自JsonToDart的代码

class CompanyModel {
  List<Companies> companies;

  CompanyModel({this.companies});

  CompanyModel.fromJson(Map<String, dynamic> json) {
    if (json['companies'] != null) {
      companies = new List<Companies>();
      json['companies'].forEach((v) {
        companies.add(new Companies.fromJson(v));
      });
    }
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    if (this.companies != null) {
      data['companies'] = this.companies.map((v) => v.toJson()).toList();
    }
    return data;
  }
}

class Companies {
  int id;
  String name;

  Companies({this.id, this.name});

  Companies.fromJson(Map<String, dynamic> json) {
    id = json['id'];
    name = json['name'];
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    data['id'] = this.id;
    data['name'] = this.name;
    return data;
  }
}