未处理的异常：类型 'List<dynamic>' 不是类型 'List<CustomerTransactionDetail>' 的子类型

Question

customerDetailGet['customer_transaction_detail']

接收数组列表如何将数组列表分配给模型

的 CustomerTransactionDetail 列表

完整代码

实际使用提供者。我有 Customer Transaction Detail 模型，所以我想分配新的接收列表数组，也添加到以前的 CustomerTransactionDetail 列表中但是错误

var url = Uri.https(BaseUrl.apiBaseUrl,
          BaseUrl.apiBaseUrlSecond + 'add_customer.php', {});
      Map object = {
        "c_name": nameController.text,
        "c_mobile": mobileController.text,
        "c_address": addressController.text,
        "login_id": Constants.loginId,
      };
      var source = await http.post(url, body: jsonEncode(object));
      if (source.statusCode == 200) {
        if (jsonDecode(source.body)["status"] == 200) {
          var message = jsonDecode(source.body)["result"]["message"];
          var customerDetailGet =
              jsonDecode(source.body)["result"]["customer_detail"];
          var customerDetail = CustomerDetail(
            accountType: customerDetailGet['account_type'],
            address: customerDetailGet['address'],
            conversationNo: customerDetailGet['conversation_no'],
            currentBalance: customerDetailGet['current_balance'],
            customerTransactionDetail: customerDetailGet['customer_transaction_detail'], // error line
            id: customerDetailGet['id'],
            mobile: customerDetailGet['mobile'],
            name: customerDetailGet['name'],
            status: customerDetailGet['status'],
          );
          int debitBalance = jsonDecode(source.body)["result"]
              ["credit_debit_balance"]["debit_balance"];
          int creditBalance = jsonDecode(source.body)["result"]
              ["credit_debit_balance"]["credit_balance"];
          Provider.of<CustomerAndTransactionClassProvider>(context,
                  listen: false)
              .addCustomer(customerDetail, debitBalance, creditBalance);
          setState(() {
            responseResult = message;
            isLoadding = false;
          });
          Navigator.pop(context);
        } else if (jsonDecode(source.body)["status"] == 202) {
          setState(() {
            responseResult = jsonDecode(source.body)["result"]["message"];
            isLoadding = false;
          });
        } else {
          setState(() {
            responseResult = "sorry try again";
            isLoadding = false;
          });
        }}

Answer 1

您必须指定变量的类型customerDetailGet。如果你不这样做，Dart 会假设它是一个 dynamic 并且可能无法按照你想要的方式处理它（这会导致你得到异常）。

指定类型最简单的方法是这样写：

List<CustomerTransactionDetail> customerDetailGet = List<CustomerTransactionDetail>.from(
  jsonDecode(source.body)["result"]["customer_detail"]
);

但是，如果 CustomerTransactionDetail 不是其中一种基本类型的子类型，这可能会失败。因此，您可能必须创建一个新列表并实例化所有值：

List<CustomerTransactionDetail> customerDetailGet = List<CustomerTransactionDetail>.from(
  jsonDecode(source.body)["result"]["customer_detail"].map(
    (customerDetail) => CustomerTransactionDetail.fromJson(customerDetail)
  )
);

在这种情况下，您将必须实施 factory constructor CustomerTransactionDetail.fromJson。

未处理的异常：类型 'List<dynamic>' 不是类型 'List<CustomerTransactionDetail>' 的子类型

Unhandled Exception: type 'List<dynamic>' is not a subtype of type 'List<CustomerTransactionDetail>'

list

dynamic

flutter