flutter - 使用 todo 模块颤动/放大错误

Question

我正在按照教程进行放大和颤动，但遇到了一些控制台错误。我关注这个https://docs.amplify.aws/start/getting-started/integrate/q/integration/flutter#creating-a-todo

我似乎无法清除错误。我将 amplify core 更改为 amplify_flutter，这似乎清除了一些错误，但现在它说我的 todo 模块有错误。

任何帮助都会有所帮助。

这是控制台中的错误

lib/main.dart:41:8: Error: Type 'Todo' not found.                       
  List<Todo> _todos = [];                                               
       ^^^^                                                             
lib/main.dart:146:14: Error: Type 'Todo' not found.                     
  final List<Todo> todos;                                               
             ^^^^                                                       
lib/main.dart:162:9: Error: Type 'Todo' not found.                      
  final Todo todo;                                                      
        ^^^^                                                            
lib/main.dart:41:8: Error: 'Todo' isn't a type.                         
  List<Todo> _todos = [];                                               
       ^^^^                                                             
lib/main.dart:70:47: Error: The getter 'Todo' isn't defined for the class '_TodosPageState'.
 - '_TodosPageState' is from 'package:amplified_todo/main.dart' ('lib/main.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'Todo'.
    _subscription = Amplify.DataStore.observe(Todo.classType).listen((event) {
                                              ^^^^                      
lib/main.dart:107:12: Error: 'Todo' isn't a type.                       
      List<Todo> updatedTodos = await Amplify.DataStore.query(Todo.classType);
           ^^^^                                                         
lib/main.dart:107:63: Error: The getter 'Todo' isn't defined for the class '_TodosPageState'.
 - '_TodosPageState' is from 'package:amplified_todo/main.dart' ('lib/main.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'Todo'.
      List<Todo> updatedTodos = await Amplify.DataStore.query(Todo.classType);
                                                              ^^^^      
lib/main.dart:125:8: Error: Duplicated named argument 'body'.           
       body: _isLoading                                                 
       ^^^^                                                             
lib/main.dart:146:14: Error: 'Todo' isn't a type.                       
  final List<Todo> todos;                                               
             ^^^^                                                       
lib/main.dart:155:61: Error: The argument type 'List<dynamic>' can't be assigned to the parameter type 'List<Widget>'.
 - 'List' is from 'dart:core'.                                          
 - 'Widget' is from 'package:flutter/src/widgets/framework.dart' ('../../src_code/flutter/packages/flutter/lib/src/widgets/framework.dart').
        children: todos.map((todo) => TodoItem(todo: todo)).toList())   
                                                            ^           
lib/main.dart:162:9: Error: 'Todo' isn't a type.                        
  final Todo todo;                                                      
        ^^^^                                                            
lib/main.dart:178:5: Error: 'Todo' isn't a type.                        
    Todo updatedTodo = todo.copyWith(isComplete: !todo.isComplete);     
    ^^^^                                                                
lib/main.dart:241:5: Error: 'Todo' isn't a type.                        
    Todo newTodo = Todo(                                                
    ^^^^                                                                
lib/main.dart:241:20: Error: The method 'Todo' isn't defined for the class '_AddTodoFormState'.
 - '_AddTodoFormState' is from 'package:amplified_todo/main.dart' ('lib/main.dart').
Try correcting the name to the name of an existing method, or defining a method named 'Todo'.
    Todo newTodo = Todo(                                                
                   ^^^^                                                       

main.dart 文件

// dart async library we will refer to when setting up real time updates
import 'dart:async';
// flutter and ui libraries
import 'package:flutter/material.dart';
// amplify packages we will need to use
import 'package:amplify_flutter/amplify.dart';
import 'package:amplify_datastore/amplify_datastore.dart';
// amplify configuration and models that should have been generated for you
import 'amplifyconfiguration.dart';
import 'models/ModelProvider.dart';
import 'models/UpdatedTodo.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Amplified Todo',
      home: TodosPage(),
    );
  }
}

class TodosPage extends StatefulWidget {
  @override
  _TodosPageState createState() => _TodosPageState();
}

class _TodosPageState extends State<TodosPage> {

  // subscription to Todo model update events - to be initialized at runtime
  late StreamSubscription _subscription;

  // loading ui state - initially set to a loading state
  bool _isLoading = true;

  // list of Todos - initially empty
  List<Todo> _todos = [];

  // amplify plugins
  final AmplifyDataStore _dataStorePlugin =
  AmplifyDataStore(modelProvider: ModelProvider.instance);

  @override
  void initState() {
    // kick off app initialization
    _initializeApp();
    super.initState();
  }

  @override
  void dispose() {
    // cancel the subscription when the state is removed from the tree
    _subscription.cancel();
    super.dispose();
  }

  Future<void> _initializeApp() async {
    // configure Amplify
    await _configureAmplify();

    // listen for updates to Todo entries by passing the Todo classType to
    // Amplify.DataStore.observe() and when an update event occurs, fetch the
    // todo list
    //
    // note this strategy may not scale well with larger number of entries
    _subscription = Amplify.DataStore.observe(Todo.classType).listen((event) {
      _fetchTodos();
    });

    // fetch Todo entries from DataStore
    await _fetchTodos();

    // after both configuring Amplify and fetching Todo entries, update loading
    // ui state to loaded state
    setState(() {
      _isLoading = false;
    });
  }

  Future<void> _configureAmplify() async {
    try {

      // add Amplify plugins
      await Amplify.addPlugins([_dataStorePlugin]);

      // configure Amplify
      //
      // note that Amplify cannot be configured more than once!
      await Amplify.configure(amplifyconfig);
    } catch (e) {

      // error handling can be improved for sure!
      // but this will be sufficient for the purposes of this tutorial
      print('An error occurred while configuring Amplify: $e');
    }
  }

  Future<void> _fetchTodos() async {
    try {

      // query for all Todo entries by passing the Todo classType to
      // Amplify.DataStore.query()
      List<Todo> updatedTodos = await Amplify.DataStore.query(Todo.classType);

      // update the ui state to reflect fetched todos
      setState(() {
        _todos = updatedTodos;
      });
    } catch (e) {
      print('An error occurred while querying Todos: $e');
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('My Todo List'),
      ),
      body: Center(child: CircularProgressIndicator()),
       body: _isLoading
           ? Center(child: CircularProgressIndicator())
           : TodosList(todos: _todos),
      floatingActionButton: FloatingActionButton.extended(
        onPressed: () {
          Navigator.push(
            context,
            MaterialPageRoute(builder: (context) => AddTodoForm()),
          );
        },
        tooltip: 'Add Todo',
        label: Row(
          children: [Icon(Icons.add), Text('Add todo')],
        ),
      ),
      floatingActionButtonLocation: FloatingActionButtonLocation.centerFloat,
    );
  }
}

class TodosList extends StatelessWidget {
  final List<Todo> todos;

  TodosList({required this.todos});

  @override
  Widget build(BuildContext context) {
    return todos.length >= 1
        ? ListView(
        padding: EdgeInsets.all(8),
        children: todos.map((todo) => TodoItem(todo: todo)).toList())
        : Center(child: Text('Tap button below to add a todo!'));
  }
}

class TodoItem extends StatelessWidget {
  final double iconSize = 24.0;
  final Todo todo;

  TodoItem({required this.todo});

  void _deleteTodo(BuildContext context) async {
    try {
      // to delete data from DataStore, we pass the model instance to
      // Amplify.DataStore.delete()
      await Amplify.DataStore.delete(todo);
    } catch (e) {
      print('An error occurred while deleting Todo: $e');
    }
  }

  Future<void> _toggleIsComplete() async {
    // copy the Todo we wish to update, but with updated properties
    Todo updatedTodo = todo.copyWith(isComplete: !todo.isComplete);
    try {

      // to update data in DataStore, we again pass an instance of a model to
      // Amplify.DataStore.save()
      await Amplify.DataStore.save(updatedTodo);
    } catch (e) {
      print('An error occurred while saving Todo: $e');
    }
  }

  @override
  Widget build(BuildContext context) {
    return Card(
      child: InkWell(
        onTap: () {
          _toggleIsComplete();
        },
        onLongPress: () {
          _deleteTodo(context);
        },
        child: Padding(
          padding: const EdgeInsets.all(8.0),
          child: Row(children: [
            Expanded(
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Text(todo.name,
                      style:
                      TextStyle(fontSize: 20, fontWeight: FontWeight.bold)),
                  Text(todo.description ?? 'No description'),
                ],
              ),
            ),
            Icon(
                todo.isComplete
                    ? Icons.check_box
                    : Icons.check_box_outline_blank,
                size: iconSize),
          ]),
        ),
      ),
    );
  }
}

class AddTodoForm extends StatefulWidget {
  @override
  _AddTodoFormState createState() => _AddTodoFormState();
}

class _AddTodoFormState extends State<AddTodoForm> {
  final _nameController = TextEditingController();
  final _descriptionController = TextEditingController();

  Future<void> _saveTodo() async {
    // get the current text field contents
    String name = _nameController.text;
    String description = _descriptionController.text;

    // create a new Todo from the form values
    // `isComplete` is also required, but should start false in a new Todo
    Todo newTodo = Todo(
        name: name,
        description: description.isNotEmpty ? description : null,
        isComplete: false);

    try {
      // to write data to DataStore, we simply pass an instance of a model to
      // Amplify.DataStore.save()
      await Amplify.DataStore.save(newTodo);

      // after creating a new Todo, close the form
      Navigator.of(context).pop();
    } catch (e) {
      print('An error occurred while saving Todo: $e');
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Add Todo'),
      ),
      body: Container(
        padding: EdgeInsets.all(8.0),
        child: SingleChildScrollView(
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.stretch,
            children: [
              TextFormField(
                  controller: _nameController,
                  decoration: InputDecoration(filled: true, labelText: 'Name')),
              TextFormField(
                  controller: _descriptionController,
                  decoration:
                  InputDecoration(filled: true, labelText: 'Description')),
              ElevatedButton(onPressed: _saveTodo, child: Text('Save'))
            ],
          ),
        ),
      ),
    );
  }
}

标签： flutterflutter-dependenciesaws-amplifyaws-amplify-cli