before I start, I rarely use Dart or Flutter.

So, I have an application to read data through an API, and I have a class called Service_class.dart where I declared the Endpoint:

    Future<ProductModel?> getSingleProductData() async {
  ProductModel? result;
  try {
    var finalcode = "PRD89473320";
    final response = await http.get(
      Uri.parse(
          "http://192.168.1.5/v1/api/product/read_single.php?productcode=$finalcode"),
      headers: {
        HttpHeaders.contentTypeHeader: "application/json",
      },
    );
    if (response.statusCode == 200) {
      final item = json.decode(response.body);
      result = ProductModel.fromJson(item);
    } else {
      print("error");
    }
  } catch (e) {
    log(e.toString());
  }
  return result;
}

At main.dart I have a Textfield:

        TextField(
          autofocus: true,
          controller: _textController,
          focusNode: _textNode,
          decoration: InputDecoration(
            border: OutlineInputBorder(),
          ),
        ),

Loading data (product_class.dart)

class DataClass extends ChangeNotifier {
  ProductModel? product;
  bool loading = false;

  getProductData() async {
    loading = true;
    product = (await getSingleProductData())!;
    loading = false;

    notifyListeners();
  }
}

Passing data to second screen (secondscreen.dart):

void initState() {
    super.initState();
    final productModel = Provider.of<DataClass>(context, listen: false);
    productModel.getProductData();
  }

And I would like to automatically fill out textfield value and send it to the $finalcode in Service_class.dart, then load and display on a second page.

CodePudding user response：

Instead of calling async function in initState you should use FutureBuilder. Here I pass default value to textfield in initState and call setState after view build, by that it would call FutureBuilder again and call your future function. I also modify your getSingleProductData to get initial value. like this:

class MyWidget extends StatefulWidget {
  const MyWidget({Key? key}) : super(key: key);

  @override
  State<MyWidget> createState() => _MyWidgetState();
}

class _MyWidgetState extends State<MyWidget> {
  TextEditingController controller = TextEditingController();
  @override
  void initState() {
    super.initState();

    WidgetsBinding.instance.addPostFrameCallback((_) {
      setState(() {
        controller.text = "PRD89473320";
      });
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: FutureBuilder<ProductModel?>(
            future: getSingleProductData(controller.text),
            builder: (context, snapshot) {
              switch (snapshot.connectionState) {
                case ConnectionState.waiting:
                  return Text('Loading....');
                default:
                  if (snapshot.hasError) {
                    return Text('Error: ${snapshot.error}');
                  } else {
                    ProductModel data = snapshot.data!;

                    return TextField(
                      autofocus: true,
                      controller: controller,
                      decoration: InputDecoration(
                        border: OutlineInputBorder(),
                      ),
                    );
                  }
              }
            }),
      ),
    );
  }

  Future<ProductModel?> getSingleProductData(String finalcode) async {
    ProductModel? result;
    try {
      final response = await http.get(
        Uri.parse(
            "http://192.168.1.5/v1/api/product/read_single.php?productcode=$finalcode"),
        headers: {
          HttpHeaders.contentTypeHeader: "application/json",
        },
      );
      if (response.statusCode == 200) {
        final item = json.decode(response.body);
        result = ProductModel.fromJson(item);
      } else {
        print("error");
      }
    } catch (e) {
      log(e.toString());
    }
    return result;
  }
}

CodePudding user response：

can be done like

void initState() {
  super.initState();
  final productModel = Provider.of<DataClass>(context, listen: false);
  productModel.getProductData().then((value) {
    _textController.text = ""; // your data
  });
}