Getting an error “Cannot deserialize the current J

I have a string:

[
  {
    "key": "key1",
    "value": "{'Time':'15:18:42','Data':'15:18:42'}",
    "duration": 5
  },
  {
    "key": "key1",
    "value": "{'Time':'15:18:42','Data':'15:18:42'}",
    "duration": 5
  }
]

My class in Models:

public class CPacket
{
    public string key { get; set; }
    public string value { get; set; }
    public int duration { get; set; }
}

I use Json.Net, I want to convert string bellow to Json Oject.

CPacket c = JsonConvert.DeserializeObject<CPacket>(strPostData);

But it error:

An exception of type 'Newtonsoft.Json.JsonSerializationException' occurred in Newtonsoft.Json.dll but was not handled in user code
Additional information: Cannot deserialize the current JSON array (e.g. [1,2,3]) into type 'QuoteAPI.Models.CPacket' because the type requires a JSON object (e.g. {"name":"value"}) to deserialize correctly.

回答1:

Your JSON represents an array of CPacket objects, not just a single object. You need to deserialize into a list.

List<CPacket> list = JsonConvert.DeserializeObject<List<CPacket>>(strPostData);

回答2:

    {
        var url = "http://jsonplaceholder.typicode.com/posts";

        var webClient = new WebClient();
        var responseStr = webClient.DownloadString(url);

        //JObject jResponse = JObject.Parse(responseStr);
        JArray jArray = JArray.Parse(responseStr);


        List<User> userList = new List<User>();

        foreach (var item in jArray)
        {
            User user = new User();

            user.UserID = Convert.ToInt32(item["userId"]);
            user.ID = Convert.ToInt32(item["id"]);
            user.Title = Convert.ToString(item["title"]);
            user.Body = Convert.ToString(item["body"]);

            userList.Add(user);
        }







public partial class Search : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        string url = "http://jsonplaceholder.typicode.com/posts";
        var webClient = new WebClient();
        var responseStr = webClient.DownloadString(url);
        JArray jArray = JArray.Parse(responseStr);



        List<Class1> userList = new List<Class1>();

        foreach (var item in jArray)
        {
            Class1 user = new Class1();


            user.userId = Convert.ToInt32(item["userId"]);
            user.id = Convert.ToInt32(item["id"]);
            user.title = Convert.ToString(item["title"]);
            user.body = Convert.ToString(item["body"]);

            userList.Add(user);
        }
        Repeater1.DataSource = userList;
        Repeater1.DataBind();
        var myClass = _download_serialized_json_data<List<Class1>>(url);
        WebRequest request = WebRequest.Create(url);
        WebResponse ws = request.GetResponse();
        //Stream stream1 = response.GetResponseStream();
        //StreamReader sr = new StreamReader(stream1);
        //string strsb = sr.ReadToEnd();
        //object objResponse = JsonConvert.DeserializeObject(strsb, JSONResponseType);
        DataContractJsonSerializer jsonSerializer =
                new DataContractJsonSerializer(typeof(List<Class1>));
        object objResponse = jsonSerializer.ReadObject(ws.GetResponseStream());
        List<Class1> jsonResponse
        = objResponse as List<Class1>;
        List<Class1> photos = (List<Class1>)jsonSerializer.ReadObject(ws.GetResponseStream());
    }

    private static T _download_serialized_json_data<T>(string url) where T : new()
    {
        using (var w = new WebClient())
        {
            var json_data = string.Empty;
            // attempt to download JSON data as a string
            try
            {
                json_data = w.DownloadString(url);
            }
            catch (Exception) { }
            // if string with JSON data is not empty, deserialize it to class and return its instance
            return !string.IsNullOrEmpty(json_data) ? JsonConvert.DeserializeObject<T>(json_data) : new T();
        }
    }
}



}