如何使用提供程序和sqflite数据库颤动将喜欢的项目保存在语言环境存储设备中

如何解决如何使用提供程序和sqflite数据库颤动将喜欢的项目保存在语言环境存储设备中

大家好，我在这里遇到问题，我使用提供程序包在“收藏夹”页面中添加了收藏夹项目，工作正常，因此当我重新启动应用程序“收藏夹项目”时，我想将其保留在语言环境存储中，有人可以帮助我解决使用sqlite数据库会出现此问题。

感谢您解决这个问题

这是使用提供商最喜欢的模型

class FavoriteItem {

   String id;
   String image;
   String title;
   String typeFood;
   String timeFood;
   double price;

   FavoriteItem(this.id,this.image,this.title,this.typeFood,this.timeFood,this.price);


}

class Favorite with ChangeNotifier{


  Map<String,FavoriteItem> _items = {};

  Map<String,FavoriteItem> get items {
    return {..._items};
  }

  int get itemCount {
    return _items.length;
  }


  void addFavoriteItem(String foodId,String foodImage,String foodTitle,String foodType,String foodTime,double foodPrice){

    if(_items.containsKey(foodId)){

      _items.update(foodId,(existingFavoriteItem) =>

          FavoriteItem(
               DateTime.Now().toString(),existingFavoriteItem.image,existingFavoriteItem.title,existingFavoriteItem.typeFood,existingFavoriteItem.timeFood,existingFavoriteItem.price
          )
      );

    }else {
       _items.putIfAbsent(
          foodId,() =>
                  FavoriteItem(

             DateTime.Now().toString(),foodImage,foodTitle,foodType,foodTime,foodPrice,));
    }

    notifyListeners();
  }

 

     void removeItem(String id) {
        _items.remove(id);
        notifyListeners();
      }
    
    
      void clear() {
        _items = {};
        notifyListeners();
      }
    }

这是收藏页面

class FavoritePage extends StatefulWidget {
  @override
  _FavoritePageState createState() => _FavoritePageState();
}

class _FavoritePageState extends State<FavoritePage> {


  @override
  Widget build(BuildContext context) {

    final favorite = Provider.of<Favorite>(context);

    return Scaffold(
        backgroundColor: Color(0xffFFFAEE),body: SafeArea(
          child: Column(
            children: <Widget>[
              Padding(
                padding: const EdgeInsets.all(15),child: Row(
                  mainAxisAlignment: MainAxisAlignment.spaceBetween,children: <Widget>[
                    Text(
                      "Your Favorite Foods",style: TextStyle(
                          fontSize: 20,fontWeight: FontWeight.bold,color: Color(0xff544646)
                      ),),Row(
                      children: <Widget>[
                        Tooltip(
                          message: "Delete All",textStyle: TextStyle(
                              fontWeight: FontWeight.bold,color: Color(0xffFfdb84)
                          ),decoration: Boxdecoration(
                              color: Colors.black,borderRadius: BorderRadius.circular(6)
                          ),child: GestureDetector(
                            onTap: (){
                              showDialog(
                                  context: context,builder: (BuildContext context) => AlertDialog(
                                    title: Text(
                                      "Do you want delete this food?",style: TextStyle(
                                          fontSize: 18,color: Color(0xff544646),fontWeight: FontWeight.w600
                                      ),shape: RoundedRectangleBorder(
                                        borderRadius: BorderRadius.all(Radius.circular(15))
                                    ),backgroundColor: Color(0xffFFFAEE),actions: <Widget>[
                                      FlatButton(
                                          onpressed: (){
                                            Navigator.of(context).pop(false);
                                          },child: Text(
                                            "No",style: TextStyle(
                                                color: Colors.black,fontWeight: FontWeight.bold
                                            ),)
                                      ),FlatButton(
                                          onpressed: (){
                                            Navigator.of(context).pop(true);
                                            Provider.of<Favorite>(context,listen: false).clear();
                                          },child: Text(
                                            "Yes",)
                                      )
                                    ],)
                              );

                            },child: Container(
                              height: 40,width: 40,decoration: Boxdecoration(
                                  color: Color(0xffFfdb84),borderRadius: BorderRadius.circular(100)
                              ),child: Icon(
                                Icons_BottomBar.delete,size: 22,],SizedBox(
                height: 10,Expanded(
                // If favorite items is empty show image and text " favorite is empty "
                child: favorite.items.isEmpty
                    ? Column(
                  mainAxisAlignment: MainAxisAlignment.center,children: <Widget>[
                    Container(
                      height: 260,width: 260,child: SvgPicture.asset(
                            favorite_empty
                        )),Text(
                      "Favorite is Empty",style: TextStyle(
                        fontSize: 20,)
                  ],)

                // else
                    :ListView.builder(
                    itemCount: favorite.items.length,itemBuilder: (context,index) =>
                    FavoriteCardItem(
                      favorite.items.values.toList()[index].id,favorite.items.keys.toList()[index],favorite.items.values.toList()[index].image,favorite.items.values.toList()[index].title,favorite.items.values.toList()[index].typeFood,favorite.items.values.toList()[index].timeFood,favorite.items.values.toList()[index].price,)
                ),SizedBox(
                height: 70,)

    );
  }
}

单击“将收藏夹添加到收藏夹页面”时，这是收藏夹图标

Padding(
                            padding: const EdgeInsets.only(right: 10),child: GestureDetector(
                              onTap: () async {
                                setState(() {
                                  ispressed = true;
                                });
                                Scaffold.of(context).showSnackBar(SnackBar(
                                  backgroundColor: Colors.black,content: Text(
                                    "Item Added to Favorite",style: TextStyle(
                                        color: Color(0xffFfdb84)
                                    ),duration: Duration(seconds: 3),));
                               favorite.addFavoriteItem(
                                   loadFood.id,loadFood.image,loadFood.title,loadFood.typeFood,loadFood.timeFood,loadFood.price
                               );

                               // await helper.createFavorite(favorite.favoriteItem);

                              },child: Container(
                                height: 35,width: 35,decoration: Boxdecoration(
                                    borderRadius: BorderRadius.circular(20),color: Color(0xffFfdb84)
                                ),// active favorite icon when clicked
                                child: (ispressed)
                                    ?Icon(Icons.favorite,size: 20,color: Color(0xffff124d))
                                    :Icon(Icons.favorite_border,color: Color(0xffff124d)),

here is screenshot about favorite page

解决方法

您应该保存ID列表。方法如下：

// Shared preferences : favorites list key
const favoritesKey = "FAVORITES_KEY";
    
// Turn the list of favorites into a list of their id
var ids = <String>[ for(var item in items) item.id ];
    
SharedPreferences prefs = await SharedPreferences.getInstance();
    
// Save the list
prefs.setStringList(favoritesKey,ids);
    
// Retrieve the list
var ids = prefs.getStringList(favoritesKey);