I'm using Provider to receive data to a screen and i have a function with not required parameters in my provider class and the data came normally. I have an icon in the appbar to open a bottomsheet, which i gave a parameter to the function so i press a button in the bottomsheet to update the existing data with the new data. I tried many times but it did not work with me because i still learning state management using provider. Can any one tell me how to it programmaticallye ?

Here's the code..

     import 'package:conditional_builder_null_safety/conditional_builder_null_safety.dart';
      import 'package:flutter/cupertino.dart';
     import 'package:flutter/material.dart';
     import 'package:provider/provider.dart';
     import 'package:rick_and_morty/pages/character_details.dart';
       import 'package:rick_and_morty/pages/widgets/character_item.dart';
      import 'package:rick_and_morty/pages/widgets/chip_choice.dart';
      import 'package:rick_and_morty/providers/my_provides.dart';

       import '../models/users.dart';

         class HomeLayout extends StatefulWidget {
         const HomeLayout({Key? key}) : super(key: key);
  
        @override
         State<HomeLayout> createState() => _HomeLayoutState();
       }

        class _HomeLayoutState extends State<HomeLayout> {


       @override
       Widget build(BuildContext context) {
       return Scaffold(
          appBar: AppBar(
            title: const Center(child: Text('Users')),
            actions: [
              IconButton(
                  padding: const EdgeInsets.only(right: 25),
                  onPressed: (){
                    showModalBottomSheet(
                        context: context,
                        builder: (context) =>
                            Column(
                              children:  [
                                Container(
                                  alignment: Alignment.center,
                                  color: Colors.black,
                                  width: double.infinity,
                                  height: 50,
                                  child: const Text('Filter  Characters',
          style:TextStyle(
          color:Colors.white
           ,fontSize: 22),),
                                ),
                                const ChoiceChipWidget(),
                              ],
                            )
                    );

                  },
                  icon: const Icon(Icons.filter_list_sharp,size: 40,)),

            ],
          ),

          body: FutureBuilder(
                future: Provider.of<MyProvider>(context).getAllCharacters(),
                  builder: (context, snapshot){
                    if(snapshot.hasData){
                      List<RickModel> users = snapshot.data!;
                      return GridView.builder(
                          gridDelegate:  const SliverGridDelegateWithFixedCrossAxisCount(
                            crossAxisCount: 2,
                            childAspectRatio: 2 / 3,
                            crossAxisSpacing: 1,
                            mainAxisSpacing: 1,
                          ),
                          itemCount: users.length,
                          itemBuilder: (context,index) =>
                              CharacterItem(
                                rickModel: users[index],
                                widget:CharacterDetails(rickModel: users[index]),
                              )
                      );
                    } else{
                      return Center(child: CircularProgressIndicator());
                    }
                  }
              )

      );


        }
        }

      import 'package:flutter/material.dart';

      import '../models/users.dart';
        import '../repository/my_repository.dart';

      class MyProvider extends ChangeNotifier{
       MyProvider(this._myRepository);

        final MyRepository _myRepository;


        List<RickModel> _allRickCharacters =[];

        List<RickModel> get allRickCharacters => _allRickCharacters;

        Future<List<RickModel>> getAllCharacters({String? species, String? gender, String? status }) async{
        await _myRepository.getAllCharacters(species: species, gender: gender, status: status)
        .then((allRickCharacters){
       _allRickCharacters = allRickCharacters;
       });
        return _allRickCharacters;

      }


       }

any one can help me in this issue?

CodePudding user response：

I think it just missing notifyListeners. Also you dont need to use await and .then at the same time. I will prefer await

  Future<List<RickModel>> getAllCharacters({
    String? species,
    String? gender,
    String? status,
  }) async {
    final allRickCharacters = await _myRepository.getAllCharacters(
        species: species, gender: gender, status: status);
    _allRickCharacters = allRickCharacters;
    notifyListeners(); //this
    return _allRickCharacters; // we may can skip return
  }

CodePudding user response：

To update data in your Flutter app using the Provider package, you can follow these steps:

Create a model class for your data. This should contain the fields that you want to update, as well as any additional methods or functions that you need to manipulate the data.

Create a provider class that will manage the data. This class should contain a reference to your data model, as well as any methods that you will use to update the data.

In your main app, wrap your app in a ChangeNotifierProvider, passing in an instance of your provider class as the value. This will allow you to access the provider class from any widget in your app using Provider.of.

In the widget where you want to update the data, use Provider.of to access the provider class and call the update method. You can pass any necessary parameters to this method to update the data in your model.

For example, in your case, you might have a method in your provider class called update characters that takes a list of RickModel objects as a parameter and updates the _allRickCharacters field in your provider class. You could then call this method from your widget like this:

Provider.of<MyProvider>(context, listen: false).updateCharacters(newCharacters);

This would update the data in your provider class and trigger a rebuild of any widgets that depend on the data.

I hope this helps! Let me know if you have any further questions or need more information.