flutter - ScopedModel - 如何传递多个模型

Question

在示例中，我们像这样传递单个模型

return ScopedModel<CounterModel>(
  model: CounterModel(), // only one model here
  child: MaterialApp(
    title: 'Scoped Model Demo',
    home: CounterHome('Scoped Model Demo'),
  ),
);

如何传递一些模型而不是单个模型？以便以后以这种方式使用它们

Widget build(BuildContext context) {
    final username =
      ScopedModel.of<UserModel>(context, rebuildOnChange: true).username;
    final counter =
      ScopedModel.of<CounterModel>(context, rebuildOnChange: true).counter;

    return Text(...);
}

Answer 1

您可以复制粘贴并运行下面的完整代码。
您可以参考此https://newcodingera.com/scoped-model-in-flutter/
您可以传递您的三个模型并将它们嵌套包装

代码片段

void main() {
  runApp(MyApp(
    counterModel: CounterModel(),
    userModel: UserModel('Brian'),
    dataModel: DataModel('this is test'),
  ));
}

class MyApp extends StatelessWidget {
  final CounterModel counterModel;
  final UserModel userModel;
  final DataModel dataModel;

  const MyApp({
    Key key,
    @required this.counterModel,
    @required this.userModel,
    @required this.dataModel,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    // At the top level of our app, we'll, create a ScopedModel Widget. This
    // will provide the CounterModel to all children in the app that request it
    // using a ScopedModelDescendant.
    return ScopedModel<DataModel>(
      model: dataModel,
      child: ScopedModel<UserModel>(
        model: userModel,
        child: ScopedModel<CounterModel>(
          model: counterModel,

工作演示

完整代码

import 'package:flutter/material.dart';
import 'package:scoped_model/scoped_model.dart';

void main() {
  runApp(MyApp(
    counterModel: CounterModel(),
    userModel: UserModel('Brian'),
    dataModel: DataModel('this is test'),
  ));
}

class MyApp extends StatelessWidget {
  final CounterModel counterModel;
  final UserModel userModel;
  final DataModel dataModel;

  const MyApp({
    Key key,
    @required this.counterModel,
    @required this.userModel,
    @required this.dataModel,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    // At the top level of our app, we'll, create a ScopedModel Widget. This
    // will provide the CounterModel to all children in the app that request it
    // using a ScopedModelDescendant.
    return ScopedModel<DataModel>(
      model: dataModel,
      child: ScopedModel<UserModel>(
        model: userModel,
        child: ScopedModel<CounterModel>(
          model: counterModel,
          child: MaterialApp(
            title: 'Scoped Model Demo',
            home: CounterHome('Scoped Model Demo'),
          ),
        ),
      ),
    );
  }
}

// Start by creating a class that has a counter and a method to increment it.
//
// Note: It must extend from Model.
class CounterModel extends Model {
  int _counter = 0;

  int get counter => _counter;

  void increment() {
    // First, increment the counter
    _counter++;

    // Then notify all the listeners.
    notifyListeners();
  }
}

class UserModel extends Model {
  String _username;

  UserModel(String username) : _username = username;

  String get username => _username;

  set username(String newName) {
    _username = newName;
    notifyListeners();
  }
}

class DataModel extends Model {
  String _data;

  DataModel(String data) : _data = data;

  String get data => _data;

  set data(String newData) {
    _data = newData;
    notifyListeners();
  }
}

class CounterHome extends StatelessWidget {
  final String title;

  CounterHome(this.title);

  @override
  Widget build(BuildContext context) {
    final counter =
        ScopedModel.of<CounterModel>(context, rebuildOnChange: true).counter;
    final userModel = ScopedModel.of<UserModel>(context, rebuildOnChange: true);
    final dataModel = ScopedModel.of<DataModel>(context, rebuildOnChange: true);

    return Scaffold(
      appBar: AppBar(
        title: Text(title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text('${userModel.username} pushed the button this many times:'),
            Text('${dataModel.data} From data model'),
            // Create a ScopedModelDescendant. This widget will get the
            // CounterModel from the nearest parent ScopedModel<CounterModel>.
            // It will hand that CounterModel to our builder method, and
            // rebuild any time the CounterModel changes (i.e. after we
            // `notifyListeners` in the Model).
            Text('$counter', style: Theme.of(context).textTheme.display1),
            Padding(
              padding: const EdgeInsets.all(8.0),
              child: RaisedButton(
                child: Text('Change Username'),
                onPressed: () {
                  userModel.username = 'Suzanne';
                },
              ),
            ),
            Padding(
              padding: const EdgeInsets.all(8.0),
              child: RaisedButton(
                child: Text('Change Data'),
                onPressed: () {
                  dataModel.data = 'data changed';
                },
              ),
            )
          ],
        ),
      ),
      // Use the ScopedModelDescendant again in order to use the increment
      // method from the CounterModel
      floatingActionButton: ScopedModelDescendant<CounterModel>(
        builder: (context, child, model) {
          return FloatingActionButton(
            onPressed: model.increment,
            tooltip: 'Increment',
            child: Icon(Icons.add),
          );
        },
      ),
    );
  }
}