flutter - 将新对象插入列表后如何更新 ListView？

Question

我尝试使用 GetBuilder 更新状态，但无法正常工作。如果我执行热重载，新对象在列表中可见，但页面未填充新项目。我应该重新加载页面还是应该使用响应式 Observable？此外，当我尝试使用 foodList.obs 使食物列表可观察时 - 我收到错误，因为我无法使食物类型对象可观察。很奇怪。

class FoodsController extends GetxController {
  List<Food> foodList = [];
  int nrOfFoods;

  onInit() {
    foodList.add(Food(name: 'banana', type: 'fruits'));
    foodList.add(Food(name: 'apples', type: 'fruits'));
    foodList.add(Food(name: 'melon', type: 'fruits'));
    super.onInit();
  }

  @override
  void onReady() {
    nrOfFoods.obs;
    super.onReady();
  }
  void addItem(Food item) {
    foodList.add(item);
    nrOfFoods = foodList.length;
    update();
  }
}

class HomePage extends StatelessWidget {
  FoodsController foodsController = Get.put(FoodsController());
  @override
  Widget build(BuildContext context) {
    print(foodsController.foodList);
    return Scaffold(
      appBar: AppBar(
        title: Text('App Bar'),
      ),
      body: Column(
        children: [
          Expanded(
            child: GetBuilder<FoodsController>(
              init: FoodsController(),
              builder: (_) => ListView.builder(
                itemCount: foodsController.foodList.length,
                itemBuilder: (BuildContext context, int index) {
                  return ListTile(
                      title: Text(foodsController.foodList[index].name));
                },
              ),
            ),
          ),
          FloatingActionButton(
            child: Text("test"),
            onPressed: () => {
              foodsController.foodList.add(Food(name: "chicken", type: "meat")),
              Get.to(SecondPage())
            },
          ),
        ],
      ),
    );
  }
}

谢谢

Answer 1

我找到了解决方案。我将控制器移到了第二页，现在可以了，尽管我认为我应该使用 Obx 而不是 GetBuilder 来使这个反应。

class Food {
  Food({this.name, this.type});
  String name, type;

  @override
  String toString() => '${this.name} is a ${this.type}';
}

class FoodsController extends GetxController {
  final List<Food> foodList = [];
  int nrOfFoods = 0;

  onInit() {
    foodList.add(Food(name: 'banana', type: 'fruits'));
    foodList.add(Food(name: 'apples', type: 'fruits'));
    foodList.add(Food(name: 'melon', type: 'fruits'));
    super.onInit();
  }

  void addItem(Food item) {
    foodList.add(item);
    nrOfFoods = foodList.length;
    update();
  }
}

class HomePage extends StatelessWidget {
  final FoodsController foodsController = Get.put(FoodsController());

  @override
  Widget build(BuildContext context) {
    print(foodsController.foodList);
    return Scaffold(
      appBar: AppBar(
        title: Text('App Bar'),
      ),
      body: Column(
        children: [
          FloatingActionButton(
            child: Text("test"),
            onPressed: () {
              foodsController.foodList.add(Food(name: "chicken", type: "meat"));
              Get.to(SecondPage());
            },
          ),
        ],
      ),
    );
  }
}

class SecondPage extends StatelessWidget {
  final FoodsController ctrl = Get.find();
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('App Bar'),
      ),
      body: Column(
        children: [
          Expanded(
            child: GetBuilder<FoodsController>(
              builder: (_) => ListView.builder(
                itemCount: ctrl.foodList.length,
                itemBuilder: (BuildContext context, int index) {
                  return ListTile(title: Text(ctrl.foodList[index].name));
                },
              ),
            ),
          ),
          FloatingActionButton(
            child: Text("test"),
            onPressed: () {
              ctrl.foodList.add(Food(name: "chicken", type: "meat"));
              Get.to(SecondPage());
            },
          ),
        ],
      ),
    );
  }
}

谢谢