无法将当前JSON数组（例如[1,2,3]）反序列化为类型”，因为该类型需要JSON对象（例如{“ name”：“ value”}）

Question

I got

"Cannot deserialize the current JSON array (eg [1,2,3]) into type '' because the type requires a JSON object (eg {"name":"value"}) to deserialize correctly" Error

I looked through most of the similar questions but found no answer to what I'm looking for, so I'm asking a new one.

Here is my JSON:

{
    "coord": {
        "lon": 105.84,
        "lat": 21.59
    },
    "weather": [
        {
            "id": 500,
            "main": "Rain",
            "description": "light rain",
            "icon": "10n"
        }
    ],
    "base": "stations",
    "main": {
        "temp": 20.31,
        "pressure": 1010.36,
        "humidity": 98,
        "temp_min": 20.31,
        "temp_max": 20.31,
        "sea_level": 1026.71,
        "grnd_level": 1010.36
    },
    "wind": {
        "speed": 1.86,
        "deg": 124.5
    },
    "rain": {
        "3h": 0.3075
    },
    "clouds": {
        "all": 92
    },
    "dt": 1482264413,
    "sys": {
        "message": 0.0114,
        "country": "VN",
        "sunrise": 1482190209,
        "sunset": 1482229157
    },
    "id": 1566319,
    "name": "Thai Nguyen",
    "cod": 200
}

And here is my code:

 private void Form1_Load(object sender, EventArgs e)
 {
     string url = "http://api.openweathermap.org/data/2.5/weather?q=London&units=metric&appid={MyAppID}";
     HttpWebRequest httpWebRequset = (HttpWebRequest)WebRequest.Create(url);
     httpWebRequset.Method = WebRequestMethods.Http.Get;
     httpWebRequset.ContentType = "application/json";

     HttpWebResponse httpResponse = (HttpWebResponse)httpWebRequset.GetResponse();

     using (var StreamReader = new StreamReader(httpResponse.GetResponseStream()))
     {
         string responseString = StreamReader.ReadToEnd();

         ResponseData data = JsonConvert.DeserializeObject<ResponseData>(responseString);

         ShowTemp.Text = data.main.temp + "°C";
         ShowWheater.Text = data.weather.description;
    }
}

When ever I try to get a temperature I can find it, but when I want to get the description from:

{
    ...
    "weather": [
        {
            "id": 500,
            "main": "Rain",
            "description": "light rain",
            "icon": "10n"
        }
    ]
    ...
}

I get the error.

Answer 1

The JSON contains an array of Weather , even if it only has one entry. This is denoted by the square brackets, see below:

"weather" : [ { "id":500, "main":"Rain", "description":"light rain", "icon":"10n" } ]

You said this was your ResponseData class:

class ResponseData 
{ 
    public Main main; 
    public Weather weather; 
} 

class Main 
{ 
    public string temp; 
} 

class Weather 
{ 
    public string description; 
}

Change the ResponseData class to this:

public class ResponseData 
{ 
    public Main main { get; set; } 
    public List<Weather> weather { get; set; } // This is a List<T> of Weather
}                                              // It can contain more than one entry 
                                               // for weather

public class Main 
{ 
    public double temp { get; set; } // This is a double
} 

public class Weather 
{ 
    public string description { get; set; }
}

You must also have a reference to System.Collections added to your project and the relevant using :

using System.Collections;

As the Weather is now a list you must access it by index like this:

ShowWeather.Text = data.weather[0].description;