Return 包含数据的对象并获取对数据的访问权限

Question

我有问题。我正在尝试创建一个对象并填充它。之后，我将 return 对象并获取数据。

对象创建成功。还有插入。但是，如果我传递（return 数据），我只会得到输出 'Instance of Object'.

我创建对象并填充它的代码：

class GetProductData {
  //get user_data from user who has create the product
  static Future<List<Object>> queryData(_userID) async {
    //collection group all collection with 'product_details'
    QuerySnapshot<Map<String, dynamic>> product_data = await FirebaseFirestore
        .instance
        .collectionGroup('product_details')
        .where('user_id', isEqualTo: _userID)
        .get();

    //map all products details into a list
    var product_data_lst = product_data.docs.map((e) => e.data()).toList();

    //object list
    List<ProductDataObject> lst_ProductDataObject = [];
    //run every list
    product_data_lst.forEach((list) {
      //add values to obejct
      lst_ProductDataObject.add(
        ProductDataObject(
            eco_shipping: list.entries.elementAt(0).value,
            business_status: list.entries.elementAt(1).value,
            fairtrade: list.entries.elementAt(2).value,
            sub_category: list.entries.elementAt(3).value,
            status_color: list.entries.elementAt(4).value,
            description: list.entries.elementAt(5).value,
            adress: list.entries.elementAt(6).value,
            stars: list.entries.elementAt(7).value,
            delivery_time: list.entries.elementAt(8).value,
            title: list.entries.elementAt(9).value,
            sell_status: list.entries.elementAt(10).value,
            eco: list.entries.elementAt(11).value,
            hashTag: list.entries.elementAt(12).value,
            user_id: list.entries.elementAt(13).value,
            price: list.entries.elementAt(14).value,
            main_category: list.entries.elementAt(14).value,
            product_id: list.entries.elementAt(15).value,
            create_date: list.entries.elementAt(16).value),
      );
    });

    //print('${lst_ProductDataObject[0].user_id.toString()}');

    return lst_ProductDataObject;
  }
}

class ProductDataObject {
  String adress;
  String business_status;
  String create_date;
  int delivery_time;
  String description;
  bool eco;
  bool eco_shipping;
  bool fairtrade;
  List<dynamic> hashTag;
  String product_id;
  String main_category;
  String price;
  String sell_status;
  int stars;
  int status_color;
  String sub_category;
  String title;
  String user_id;

  ProductDataObject({
    required this.adress,
    required this.business_status,
    required this.create_date,
    required this.delivery_time,
    required this.description,
    required this.eco,
    required this.eco_shipping,
    required this.fairtrade,
    required this.hashTag,
    required this.product_id,
    required this.main_category,
    required this.price,
    required this.sell_status,
    required this.stars,
    required this.status_color,
    required this.sub_category,
    required this.title,
    required this.user_id,
  });
}

这是我的代码，我在其中尝试获取对象数据：

//load product lst
            Container(
              child: FutureBuilder<List<Object>>(
                future: GetProductData.queryData(_userID),
                builder: (BuildContext context,
                    AsyncSnapshot<List<Object>> snapshot) {
                  if (snapshot.hasError) {
                    return Container(
                      child: Column(
                        children: [],
                      ),
                    );
                  } else if (snapshot.hasData) {
                    return customText(snapshot.data.toString(), Colors.black,
                        18, FontWeight.normal, null);

                    //customText(snapshot.error.toString(), Colors.black,
                    //18, FontWeight.normal, null);
                  } else {
                    return customText('No data found...', Colors.black, 18,
                        FontWeight.normal, null);
                  }
                },
              ),
            ),

输出如下所示：

有谁知道我如何 return 对象并在 return 之后获取数据？非常感谢 (:

Answer 1

你的 snapshot 似乎已经是 List<ProductDataObject> 试试这个：

return customText(snapshot.toString(),... //remove the ".data"

Answer 2

没关系。我有一个解决方案 (:

test(data) {
  List<ProductDataObject> object = data;

  return (object.elementAt(0).user_id.toString());
}

Return 包含数据的对象并获取对数据的访问权限

Return object with data and get access to data

get

return

object

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