在 Flutter GetX 中使用不带 controller 的可观察变量

Question

Something that I didn't completely understand about the Get package is whether it is always required to put the observable variables in a controller. For example, this case works:

 import 'package:flutter/material.dart'; import 'package:get/get.dart'; void main() => runApp(App()); class App extends StatelessWidget { final isTrue = true.obs; @override Widget build(BuildContext context) { return MaterialApp( title: 'Demo', theme: ThemeData( visualDensity: VisualDensity.adaptivePlatformDensity, ), home: Scaffold( body: Center( child: Obx( () => FlatButton( color: isTrue.value? Colors.blue: Colors.red, child: Text('Hey'), onPressed: () => isTrue.value =.isTrue,value, ), ), ), ); ); } }

But would there be leaks/problems, because of this and is a GetXController necessary in this situation?

Answer 1

So as @Baker explained with his comments, the obs streams should be destroyed through the GetXControllers and they will persist in memory, if used independently in a stateless widget.

Answer 2

Yes, you can achieve using an Rx<T> observable in your UI, without using any GetxController , with the ObxValue widget which comes with the Getx package:

you can use it like this:

ObxValue<RxInt>(
          (data) => GestureDetector(
            onTap: () {
              data.value++;
            },
            child: Text("${data.value}"),
          ),
          0.obs,
        ),

as you see, you need to specify the type of the ObxValue 's Rx<T> , in my case I specified RxInt , then its an initial value which is 0.obs , and in the builder, you can return a widget and manage the value of it, and it will update automatically.

Note: the ObxValue manage automatically it's lifecycle, when the widget is moved from the tree ( disposed ), also the observable will dispose / close automatically.