需要将此 model object 从 Json 格式转换为 Z35900D987289A83AF101D18A9F7C

Question

dart 的新手只需使用 from 方法将 model object 转换为 ZEED8D85B888A6C01333424J8ZEE6 格式。 如何通过构造函数发送此数据以在 dart 中描述相同的内容，就像使用来自 firebase 的这些 model 对象一样。 包含整本书 Model Class 到其中。 需要帮忙。 谢谢你。

导入“飞镖：转换”；

导入“包：get/get.dart”；

class Book {
  Book({
    required this.author,
    required this.bookID,
    required this.discountPercentage,
    required this.description,
    required this.title,
    required this.itemCount,
    required this.price,
    this.isLiked = false,
    required this.ratings,
    required this.coverImage,
  });
  late String author;
  late String bookID;
  late int discountPercentage;
  late String description;
  late String title;
  late double price;
  late double ratings;
  late bool isLiked;
  var itemCount = 0.obs;
  late String coverImage;
  bool? isRecommended = false;
  Book.fromJson(Map<String, dynamic> json, this.bookID) {
    author = json['author'];
    bookID = json['bookID'];
    discountPercentage = json['discountPercentage'];
    itemCount = json['itemCount'];
    description = json['description'];
    title = json['title'];
    price = json['price'];
    isLiked = false;
    ratings = json['ratings'];
    coverImage = json['coverImage'];
    isRecommended = json['isRecommended'];
  }
  Book.fromSnapShot(var firestoreSnapshot) {
    author = firestoreSnapshot['author'];
    bookID = firestoreSnapshot['bookID'];
    discountPercentage = firestoreSnapshot['discountPercentage'];
    itemCount = firestoreSnapshot['itemCount'];
    description = firestoreSnapshot['description'];
    title = firestoreSnapshot['title'];
    price = firestoreSnapshot['price'];
    isLiked = false;
    ratings = firestoreSnapshot['ratings'];
    coverImage = firestoreSnapshot['coverImage'];
  }

  Map<String, dynamic> toJson() {
    final _data = <String, dynamic>{};
    _data['author'] = author;
    _data['bookID'] = bookID;
    _data['discountPercentage'] = discountPercentage;
    _data['description'] = description;
    _data['title'] = title;
    _data['price'] = price;
    _data['coverImage'] = coverImage;
    _data['itemCount'] = itemCount;
    return _data;
  }

  setItemcount(int count) {
    itemCount.value = count;
  }
}



Future getBooks() async {
    RxInt itemCount = 1.obs;
    QuerySnapshot querySnapshot =
        await FirebaseFirestore.instance.collection("books").get();

    var bookList = [];
    for (var doc in querySnapshot.docs) {
      Book book = Book(
        author: doc['author'],
        title: doc['title'],
        price: doc['price'].toDouble(),
        coverImage: doc['coverImage'],
        bookID: doc.id,
        ratings: doc['ratings'].toDouble(),
        description: doc['description'],
        discountPercentage: doc['discountPercentage'],
        isLiked: false,
        itemCount: itemCount,
      );
      bookList.add(book);
    }
    return bookList;
  }



Book.fromJson(Map<String, dynamic> json, this.bookID) {
    author = json['author'];
    bookID = json['bookID'];
    discountPercentage = json['discountPercentage'];
    itemCount = json['itemCount'];
    description = json['description'];
    title = json['title'];
    price = json['price'];
    isLiked = false;
    ratings = json['ratings'];
    coverImage = json['coverImage'];
    isRecommended = json['isRecommended'];
  }

Answer 1

您可以使用此 model class，如果您需要更新项目使用.copyWith并重新分配它

从 DocumentSnapshot 读取将是

factory Book.fromFirestore(
    DocumentSnapshot<Map<String, dynamic>> snapshot,
    SnapshotOptions? options,
  ) {
    final map = snapshot.data();
    return Book(
      author: map?['author'] ?? '',
      bookID: map?['bookID'] ?? '',
      discountPercentage: map?['discountPercentage']?.toInt() ?? 0,
      description: map?['description'] ?? '',
      title: map?['title'] ?? '',
      price: double.tryParse(map?['price']) ?? 0.0,
      ratings: double.tryParse(map?['ratings']) ?? 0.0,
      isLiked: map?['isLiked'] ?? false,
      itemCount: int.tryParse(map?['itemCount']) ?? 0,
      coverImage: map?['coverImage'] ?? '',
      isRecommended: map?['isRecommended'],
    );
  }

import 'dart:convert';

import 'package:cloud_firestore/cloud_firestore.dart';

class Book {
  final String author;
  final String bookID;
  final int discountPercentage;
  final String description;
  final String title;
  final double price;
  final double ratings;
  final bool isLiked;
  final int itemCount;
  final String coverImage;
  bool? isRecommended;
  Book({
    required this.author,
    required this.bookID,
    required this.discountPercentage,
    required this.description,
    required this.title,
    required this.price,
    required this.ratings,
    required this.isLiked,
    required this.coverImage,
    this.itemCount = 0,
    this.isRecommended = false,
  });

  Map<String, dynamic> toMap() {
    final result = <String, dynamic>{};

    result.addAll({'author': author});
    result.addAll({'bookID': bookID});
    result.addAll({'discountPercentage': discountPercentage});
    result.addAll({'description': description});
    result.addAll({'title': title});
    result.addAll({'price': price});
    result.addAll({'ratings': ratings});
    result.addAll({'isLiked': isLiked});
    result.addAll({'itemCount': itemCount});
    result.addAll({'coverImage': coverImage});
    if (isRecommended != null) {
      result.addAll({'isRecommended': isRecommended});
    }

    return result;
  }

  factory Book.fromFirestore(
    DocumentSnapshot<Map<String, dynamic>> snapshot,
    SnapshotOptions? options,
  ) {
    final map = snapshot.data();
    return Book(
      author: map?['author'] ?? '',
      bookID: map?['bookID'] ?? '',
      discountPercentage: map?['discountPercentage']?.toInt() ?? 0,
      description: map?['description'] ?? '',
      title: map?['title'] ?? '',
      price: double.tryParse(map?['price']) ?? 0.0,
      ratings: double.tryParse(map?['ratings']) ?? 0.0,
      isLiked: map?['isLiked'] ?? false,
      itemCount: int.tryParse(map?['itemCount']) ?? 0,
      coverImage: map?['coverImage'] ?? '',
      isRecommended: map?['isRecommended'],
    );
  }

  String toJson() => json.encode(toMap());

  Book copyWith({
    String? author,
    String? bookID,
    int? discountPercentage,
    String? description,
    String? title,
    double? price,
    double? ratings,
    bool? isLiked,
    int? itemCount,
    String? coverImage,
    bool? isRecommended,
  }) {
    return Book(
      author: author ?? this.author,
      bookID: bookID ?? this.bookID,
      discountPercentage: discountPercentage ?? this.discountPercentage,
      description: description ?? this.description,
      title: title ?? this.title,
      price: price ?? this.price,
      ratings: ratings ?? this.ratings,
      isLiked: isLiked ?? this.isLiked,
      itemCount: itemCount ?? this.itemCount,
      coverImage: coverImage ?? this.coverImage,
      isRecommended: isRecommended ?? this.isRecommended,
    );
  }
}