无法将 JSON 数组反序列化为类型 - Json.NET [英] Cannot deserialize JSON array into type - Json.NET
问题描述
我正在尝试将 json 数据反序列化为模型类,但失败了.这是我所做的:
I am trying to deserialize a json data into a model class but I am failing. Here is what I do:
public CountryModel GetCountries() {
using (WebClient client = new WebClient()) {
var result = client.DownloadString("http://api.worldbank.org/incomeLevels/LIC/countries?format=json");
var output = JsonConvert.DeserializeObject<List<CountryModel>>(result);
return output.First();
}
}
这是我的模型的样子:
public class CountryModel
{
public int Page { get; set; }
public int Pages { get; set; }
public int Per_Page { get; set; }
public int Total { get; set; }
public List<Country> Countries { get; set; }
}
public class Country
{
public int Id { get; set; }
public string Iso2Code { get; set; }
public string Name { get; set; }
public Region Region { get; set; }
}
public class Region
{
public int Id { get; set; }
public string Value { get; set; }
}
你可以看到我在这里得到的 Json:http://api.worldbank.org/incomeLevels/LIC/countries?format=json
You can see the Json I am getting here: http://api.worldbank.org/incomeLevels/LIC/countries?format=json
这是我得到的错误:
无法将 JSON 数组反序列化为Mvc4AsyncSample.Models.CountryModel"类型.第 1 行,位置 1.
Cannot deserialize JSON array into type 'Mvc4AsyncSample.Models.CountryModel'. Line 1, position 1.
推荐答案
你必须编写一个自定义的JsonConverter
:
You have to write a custom JsonConverter
:
public class CountryModelConverter : JsonConverter
{
public override bool CanConvert(Type objectType)
{
if (objectType == typeof(CountryModel))
{
return true;
}
return false;
}
public override object ReadJson(JsonReader reader, Type objectType
, object existingValue, JsonSerializer serializer)
{
reader.Read(); //start array
//reader.Read(); //start object
JObject obj = (JObject)serializer.Deserialize(reader);
//{"page":1,"pages":1,"per_page":"50","total":35}
var model = new CountryModel();
model.Page = Convert.ToInt32(((JValue)obj["page"]).Value);
model.Pages = Convert.ToInt32(((JValue)obj["pages"]).Value);
model.Per_Page = Int32.Parse((string) ((JValue)obj["per_page"]).Value);
model.Total = Convert.ToInt32(((JValue)obj["total"]).Value);
reader.Read(); //end object
model.Countries = serializer.Deserialize<List<Country>>(reader);
reader.Read(); //end array
return model;
}
public override void WriteJson(JsonWriter writer, object value
, JsonSerializer serializer)
{
throw new NotImplementedException();
}
}
并使用该转换器标记 CountryModel
(我还必须将一些 int
切换为 string
):
And tag the CountryModel
with that converter (I also had to switch some int
to string
):
[JsonConverter(typeof(CountryModelConverter))]
public class CountryModel
{
public int Page { get; set; }
public int Pages { get; set; }
public int Per_Page { get; set; }
public int Total { get; set; }
public List<Country> Countries { get; set; }
}
public class Country
{
public string Id { get; set; }
public string Iso2Code { get; set; }
public string Name { get; set; }
public Region Region { get; set; }
}
public class Region
{
public string Id { get; set; }
public string Value { get; set; }
}
那么你应该可以像这样反序列化:
Then you should be able to deserialize like this:
var output = JsonConvert.DeserializeObject<CountryModel>(result);
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