在 Flutter 中将 JSON 解析为模型答案

【问题标题】：Parsing JSON to a model in Flutter在 Flutter 中将 JSON 解析为模型
【发布时间】：2019-09-23 01:57:31
【问题描述】：

我有一些存储在 JSON 中的数据，我正在尝试将其映射到其各自的模型类。

{ 
"1":{ 
  "answer":"This is question 1",
  "question":"This is answer 1"
},
"2":{ 
  "answer":"This is question 2",
  "question":"This is answer 2"
},
"3":{ 
  "answer":"This is question 3",
  "question":"This is answer 3"
},
"4":{ 
  "answer":"This is question 4",
  "question":"This is answer 4"
},
"5":{ 
  "answer":"This is question 5",
  "question":"This is answer 5"
   }
}

我想将question 和answer 字段映射到模型，但是当它们嵌套在一个数字上时我该如何实现呢？通常我会创建另一个父类的模型类，但是当父类没有标记时你会怎么做？

class FaqModel {
  String question;
  String answer;

  FaqModel({this.question, this.answer});

  FaqModel.fromJson(Map<String, dynamic> json) {
    question = json["question"];
    answer = json["answer"];
  }
}

【问题讨论】：

试试这个：medium.com/@diegoveloper/…

标签： json flutter dart

【解决方案1】：

只需获取密钥并进行迭代，如下所示：


    final data = { 
"1":{ 
  "answer":"This is question 1",
  "question":"This is answer 1"
},
"2":{ 
  "answer":"This is question 2",
  "question":"This is answer 2"
},
"3":{ 
  "answer":"This is question 3",
  "question":"This is answer 3"
},
"4":{ 
  "answer":"This is question 4",
  "question":"This is answer 4"
},
"5":{ 
  "answer":"This is question 5",
  "question":"This is answer 5"
   }
};


  final models = data.keys.map((key) {
    final subData = data[key];
    return FaqModel.fromJson(subData);
  });

 models.forEach((item) {
   print("FAQ: ${item.question} \n ${item.answer}\n\n");
 });

【讨论】：

【解决方案2】：

只使用下面的模型

// To parse this JSON data, do
//
//     final faqModel = faqModelFromJson(jsonString);

import 'dart:convert';

Map<String, FaqModel> faqModelFromJson(String str) =>     Map.from(json.decode(str)).map((k, v) => MapEntry<String, FaqModel>(k,     FaqModel.fromJson(v)));

String faqModelToJson(Map<String, FaqModel> data) =>     json.encode(Map.from(data).map((k, v) => MapEntry<String, dynamic>(k, v.toJson())));

class FaqModel {
    String answer;
    String question;

    FaqModel({
        this.answer,
        this.question,
    });

    factory FaqModel.fromJson(Map<String, dynamic> json) => FaqModel(
        answer: json["answer"] == null ? null : json["answer"],
        question: json["question"] == null ? null : json["question"],
    );

    Map<String, dynamic> toJson() => {
        "answer": answer == null ? null : answer,
        "question": question == null ? null : question,
    };
}

你的 JSON

final jsonData = { 
"1":{ 
  "answer":"This is question 1",
  "question":"This is answer 1"
},
"2":{ 
  "answer":"This is question 2",
  "question":"This is answer 2"
},
"3":{ 
  "answer":"This is question 3",
  "question":"This is answer 3"
},
"4":{ 
  "answer":"This is question 4",
  "question":"This is answer 4"
},
"5":{ 
  "answer":"This is question 5",
  "question":"This is answer 5"
}
};

并解析 JSON

FaqModel faqModel = faqModelFromJson(jsonData);

【讨论】：