Question

我有这个要发送到服务器的键值对：

String brand = "sony";

  double price_val = 0.01,
      ram_val = 0.01,
      internal_val = 0.01,
      kamera_val = 0.01;

var arguments = {
  "brand": brand,
  "price": price_val,
  "ram": ram_val,
  "internal": internal_val,
  "kamera": kamera_val
};

但是我得到了这个错误：

Error : type 'double' is not a subtype of type 'String' in type cast

如果我将其更改为.toString()，则服务器将给出另一个错误，因为值必须为double。我该如何准确发送这些值？

编辑

它似乎在http请求中给出了错误：

http.post(url,
        body: arguments,
        headers: {"Content-Type": "application/json"}).then((onValue) {
      Navigator.push(
          context,
          MaterialPageRoute(
              builder: (context) => ResultPage(
                    onValue.body,
                  )));
});

Answer 1

如果您在请求标头中将application/json设置为内容类型，则需要使用jsonEncode将请求正文编码为json

这是示例

http.post(url,
        body: jsonEncode(arguments),
        headers: {"Content-Type": "application/json"}).then((onValue) {
      Navigator.push(
          context,
          MaterialPageRoute(
              builder: (context) => ResultPage(
                    onValue.body,
                  )));
});

Answer 2

明确定义参数类型

final arguments = <String, Object>{
  "brand": brand,
  "price": price_val,
  "ram": ram_val,
  "internal": internal_val,
  "kamera": kamera_val
};

Answer 3

您可以使用动态关键字：

final arguments = <String, dynamic>{
  "brand": brand,
  "price": price_val,
  "ram": ram_val,
  "internal": internal_val,
  "kamera": kamera_val
};

具有不同数据类型的飞镖键值

3 个答案: