c# - Invalidcastexception JsonConvert.DeserializeObject

Question

我收到一个无效的强制转换异常，表明指定的强制转换无效。在这条线上:

RootObject mountain = JsonConvert.DeserializeObject<RootObject>(json1);

来自documentation这应该没问题？我可以看到控制台输出正常吗？

Response: [{"Height_ft": 2999.0, "Height_m": 914.0, "ID": "c1", "Latitude": 57.588007, "Longitude": -5.5233564, "Name": "Beinn Dearg", "humidity": 0.81, "snowCover": 4.99, "temperature": 63.0}]

        Spinner spinner = (Spinner)sender;
        string urlmountain = "http://removed.azurewebsites.net/api/Mountains?name=";
        JsonValue json1 = FetchMountain(urlmountain+string.Format("{0}", spinner.GetItemAtPosition(e.Position)));
        //below.................................
        RootObject mountain = JsonConvert.DeserializeObject<RootObject>(json1); //this line
        string toast = mountain.Name;
        Toast.MakeText(this, toast, ToastLength.Long).Show();

    private JsonValue FetchMountain(string urlmountain)
    {
        // Create an HTTP web request using the URL:
        HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(new Uri(urlmountain));
        request.ContentType = "application/json";
        request.Method = "GET";

        // Send the request to the server and wait for the response:
        using (WebResponse response = request.GetResponse())
        {
            // Get a stream representation of the HTTP web response:
            using (Stream stream = response.GetResponseStream())
            {
                // Use this stream to build a JSON document object:
                JsonValue jsonDoc1 = JsonObject.Load(stream);
                Console.Out.WriteLine("Response: {0}", jsonDoc1.ToString());

                // Return the JSON document:
                return jsonDoc1;
            }
        }
    }
    public class RootObject
    {
        public string ID { get; set; }

        public double? Latitude { get; set; }

        public double? Longitude { get; set; }

        public string Name { get; set; }

        public double? Height_m { get; set; }

        public double? Height_ft { get; set; }

        public double? temperature { get; set; }

        public double? humidity { get; set; }

        public double? snowCover { get; set; }

        public override string ToString()
        {
            return Name;
        }
    }

Answer 1

返回的 json 数据是一个对象数组，而不是单个对象，如左右括号 [] 所示。您需要反序列化为数组或列表:

var mountains = JsonConvert.DeserializeObject<List<RootObject>>(json);

要从反序列化的有效负载访问第一座山，请使用 .FirstOrDefault()。

var mountain = mountains.FirstOrDefault();
if (mountain != null)
{
    string toast = mountain.Name;
    Toast.MakeText(this, toast, ToastLength.Long).Show();
}