"写入本地 json 文件"

Question

我正在创建一个允许用户保存小数据的应用程序。 我的资产文件夹中有一个 json 文件，我想创建一个可以向其写入更多 json 数据的应用程序。 路径：assets\/vault.json

Vault.json

[
  {
    "name":"Ash",
    "age":"22",
    "hobby" : "golf"
  },
  {
    "name":"philip",
    "age":"17",
    "hobby" : "fishing"
  },
  {
    "name":"charles",
    "age":"32",
    "hobby" : "drawing"
  }

]

Answer 1

您可以将其存储在应用程序的文件系统中，而不是存储在rootBundle中。 请参考这里

Answer 2

看来您无法在运行时期间写入资产中的文件（请参阅此帖子以供参考）。 本页介绍如何使用path_provider查找本地路径和读取/写入本地文件。

Answer 3

由于您无法在运行时写入资产中的文件，如前所述，请将其存储在本地计算机的其他位置。 下面的代码可以从一个json<\/strong>文件中读取并写入它——

import 'dart:io';
import 'dart:convert';

List<Player> players = [];

void main() async{
    print("hello world");
    final File file = File('D:/Sadi/../vault.json'); //load the json file
    await readPlayerData(file); //read data from json file
    
    Player newPlayer = Player(  //add a new item to data list
      'Samy Brook',
      '31',
      'cooking'
      );

  players.add(newPlayer);

  print(players.length);

  players  //convert list data  to json 
      .map(
        (player) => player.toJson(),
      )
      .toList();
      
    file.writeAsStringSync(json.encode(players));  //write (the whole list) to json file
}

Future<void> readPlayerData (File file) async { 
  
    
    String contents = await file.readAsString();
    var jsonResponse = jsonDecode(contents);
    
    for(var p in jsonResponse){
        
        Player player = Player(p['name'],p['age'],p['hobby']);
        players.add(player);
    }
    
      
}

class Player {
  late String name;
  late String age;
  late String hobby;
  

  Player(
     this.name,
     this.age,
    this.hobby,
  
  );

  Player.fromJson(Map<String, dynamic> json) {
    name = json['name'];
    age = json['age'];
    hobby = json['hobby'];
    
  }

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