Getx无法与FutureBuilder一起正常工作以获取更新列表

Question

我在项目中使用Getx控制器。我已经为FutureBuilder创建了用于显示列表的控制器，但在Future Function上没有设置.Obs。我正在共享代码。

class PPHomeController extends GetxController {
Future<List<PPProductRenterModel>> listNearProduct;
// i want to set .Obs end of the "listNearProduct" but it's not working because of Future.  
FetchNearProductList({@required int price}) async {
listNearProduct = CallGetNearProducts();// Http API Result
}
} 

{
PPHomeController _homeController = Get.put(PPHomeController());
Widget mainProductListView() {
return FutureBuilder<List<PPProductRenterModel>>
(builder: (context, AsyncSnapshot<List<PPProductRenterModel>> projectSnap){
if(!projectSnap.hasData){
if(projectSnap.connectionState == ConnectionState.waiting){
return Container(
child: Loading(),
);
}
}

return ListView.builder(
itemCount: projectSnap.data.length,
itemBuilder: (context, index) {
PPProductRenterModel model = projectSnap.data[index];
PPPrint(tag: "CheckId",value: model.productId);
return ProductMainItemRow(model);
});
},
future: _homeController.listNearProduct,);

Answer 1

在GetX中实现List有一种更干净的方法，不用担心类型转换：

实例化它：

final myList = [].obs;

分配：

myList.assignAll( listOfAnyType );

(参考(使用List.value:时的颤振错误

"value"已弃用，不应使用。List.value已弃用。使用[yourList.assignAL(newList(]。尝试替换已弃用的具有替换项的成员。

---

详细代码示例

ProductController.dart

class ProductController extends GetxController {
final productList = [].obs;
@override
void onInit() {
fetchProducts();
super.onInit();
}
void fetchProducts() async {
var products = await HttpServices.fetchProducts();
if (products != null) {
productList.assignAll(products);
}
}
}

HttpServices.dart

class HttpServices {
static var client = http.Client();
static Future<List<Product>> fetchProducts() async {
var url = 'https://link_to_your_api';
var response = await client.get(url);
if (response.statusCode == 200) {
return productFromJson(response.body);
} else {
return null;
}
}
}

product.dart

class Product {
Product({
this.id,
this.brand,
this.title,
this.price,
....
});
....
}

Answer 2

形成文档：

3-第三种更实用、更容易和首选的方法，只需添加.obs作为您价值的属性：

final items = <String>[].obs;

按照该指令，这应该可以工作：

final listNearProduct = Future.value(<PPProductRenterModel>[]).obs;

例如：

// controller
final list = Future.value(<String>[]).obs;
@override
void onInit() {
super.onInit();
fetchList();
}
Future<List<String>> callApi() async {
await Future.delayed(Duration(seconds: 2));
return ['test'];
}
void fetchList() async {
list.value = callApi();
}

// screen
@override
Widget build(BuildContext context) {
return GetX<Controller>(
init: Controller(),
builder: (controller) {
return FutureBuilder<List<String>>(
future: controller.list.value,
builder: (context, snapshot) {
if (snapshot.hasData) {
print(snapshot.data[0]); // Output: test
return Text(snapshot.data[0]);
} else if (snapshot.hasError) {
return Text("${snapshot.error}");
}
// By default, show a loading spinner.
return CircularProgressIndicator();
},
);
},
);
};

Answer 3

您实际上从未调用FetchNearProductList。

你需要在某个地方调用它，最好是在FutureBuilder使用该Future之前。