Flutter：如何将动态列表插入到 sqflite

问题描述

我在Flutter中有一个应用程序想在初始化数据库时将数据列表添加到sqlite数据库，我对模型类型有疑问。 我有这个数据模型：

import 'dart:convert';

List<Clubs> clubsFromMap(String str) =>
    List<Clubs>.from(json.decode(str).map((x) => Clubs.fromMap(x)));

String clubsToMap(List<Clubs> data) =>
    json.encode(List<dynamic>.from(data.map((x) => x.toMap())));

class Clubs {
  Clubs({
    this.id,this.club,this.leagueId,this.price,this.surname,this.leagueName,this.counter,this.selected,});

  int id;
  String club;
  int leagueId;
  String price;
  String surname;
  String leagueName;
  int counter;
  String selected;

  factory Clubs.fromMap(Map<String,dynamic> json) => Clubs(
        id: json["id"],club: json["club"],leagueId: json["league_id"],price: json["price"],surname: json["surname"],leagueName: json["league_name"],counter: json["counter"],selected: json["selected"],);

  Map<String,dynamic> toMap() => {
        "id": id,"club": club,"league_id": leagueId,"price": price,"surname": surname,"league_name": leagueName,"counter": counter,"selected": selected,};
}

我有这个模型的数据列表：

var clubs = [
    {
      "id": 1,"club": "Manchester City","league_id": 1,"price": "10.00","surname": "MCY","league_name": "Premier League","counter": 1,"selected": "No"
    },..................etc
]

不，我想将此初始数据添加到 sqflite 数据库，我创建了 :

import 'package:sqflite/sqflite.dart';
class DataBaseService {
  static final DataBaseService _instance = DataBaseService.internal();
  factory DataBaseService() => _instance;
  DataBaseService.internal();

  Database _database;
  Future<Database> get database async {
    if (_database == null) {
      _database = await intializeDataBase();
      return _database;
    }
  }

Future<Database> intializeDataBase() async {
    var dir = await getDatabasesPath();
    var path = dir + "clubs.db";
    var database =
        await openDatabase(path,version: 1,onCreate: (db,version) {
      db.execute('''
      create table $clubsTableName(
        columnId integer primary key,$columnClub text not null,$columnLeaueId integer,$columnPrice double,$columnSurname text not null,$columnLeagueName text,$columnCounter integer.
        $columnSelected text,)
      ''');
db.insert(clubsTableName,clubs.toMap());

它说 toMap() 没有定义，如果我把它改成 clubsFromMap(clubs) 而不是 clubs.toMap() 它说：The argument type 'List<Clubs>' can't be assigned to the parameter type 'Map<String,Object>'.dart(argument_type_not_assignable)

我该如何解决这个问题？

解决方法

我像这样更改列表格式后解决了它：

var clubs = {"data":{
    {
      "id": 1,"club": "Manchester City","league_id": 1,"price": "10.00","surname": "MCY","league_name": "Premier League","counter": 1,"selected": "No"
    },..................etc}
}