I`m using provider in my Flutter app. And here is my file, where I use this provider:

class WorkScreen extends StatelessWidget {
  WorkScreen({Key? key}) : super(key: key);

  final String title = 'Service Station';
  final List<Work> works = [Work('Repair Engine', 200, 0.5), Work('Repair door', 250, 1.5), Work('Repair wheels', 120, 2)];

@override
  Widget build(BuildContext context) {

    return ChangeNotifierProvider(
      create: (context) => Cart(),
      child: Scaffold(
      appBar: AppBar(
        title: Text(title),
        actions: [
          IconButton(
              onPressed: _onSettingsPressed,
              icon: const Icon(Icons.settings))
        ],
      ),
      body: WorkList(works),
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          Navigator.of(context).push(MaterialPageRoute(builder: (context) => ResultForm()));
        },
        child: const Icon(Icons.calculate)
      ),
    )
    );
  }
}

When I press floating action button the result form is appears. And here is this file:

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:service_station/screens/work_tile.dart';
import 'package:service_station/models/work_model.dart';
import 'package:provider/provider.dart';

class ResultForm extends StatelessWidget {

  String countItemsText = ' points in your cart';

  @override
  Widget build(BuildContext context) {

    var cart = context.watch<Cart>();

    return Scaffold(
      appBar: AppBar(title: Text('Result')),
      body: Padding(
        padding: const EdgeInsets.fromLTRB(15, 15, 0, 0),
        child: Column(
          children: [
            Text(countItemsText),
          ListView.separated(
            itemCount: cart.works.length,
            itemBuilder: (context, index) {
              return WorkTile(cart.works[index]);
            },
            separatorBuilder: (context, index) {
              return const Divider();
            },
          ),
          ],
        ),
      )
    );
  }
}

And when I click on this button, the app gives an error:

Error: Could not find the correct Provider<Cart> above this ResultForm Widget

Can you help me with this problem? If you need other files, write in comment.

CodePudding user response：

You need to use ChangeNotifierProvider.value to pass your ChangeNotifier (Cart) to the other page:

class WorkScreen extends StatelessWidget {
  WorkScreen({Key? key}) : super(key: key);

  final String title = 'Service Station';
  final List<Work> works = [Work('Repair Engine', 200, 0.5), Work('Repair door', 250, 1.5), Work('Repair wheels', 120, 2)];
  final Cart cartNotifier = Cart();

  @override
  Widget build(BuildContext context) {

    return ChangeNotifierProvider(
      create: (context) => cartNotifier,
      child: Scaffold(
      appBar: AppBar(
        title: Text(title),
        actions: [
          IconButton(
              onPressed: _onSettingsPressed,
              icon: const Icon(Icons.settings))
        ],
      ),
      body: WorkList(works),
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          Navigator.of(context).push(
              MaterialPageRoute(
                  builder: (context) => ChangeNotifierProvider<Cart>.value(
                      value: cartNotifier, 
                      child: ResultForm()
                  )
              )
          );
        },
        child: const Icon(Icons.calculate)
      ),
    )
    );
  }
}