Question

我正在将JSON对象反序列化为使用json2csharp创建的类。反序列化后，我将无法访问该对象的嵌套值。我得到的错误是这样的：

System.NullReferenceException：'对象引用未设置为对象的实例。'

这是我创建的课程；

public class Ticker
{
    public List<object> error { get; set; }
    public Result result { get; set; }

    public class Result
    {
        public XXBTZCAD XBTCAD { get; set; }


        public class XXBTZCAD
        {
            public List<string> a { get; set; }
            public List<string> b { get; set; }
            public List<string> c { get; set; }
            public List<string> v { get; set; }
            public List<string> p { get; set; }
            public List<int> t { get; set; }
            public List<string> l { get; set; }
            public List<string> h { get; set; }
            public string o { get; set; }
        }
    }
}

在撰写本文时，这是JSON字符串：

{
  "error": [

  ],
  "result": {
 "XXBTZCAD": {
  "a": [
    "4776.10000",
    "8",
    "8.000"
  ],
  "b": [
    "4773.90000",
    "1",
    "1.000"
  ],
  "c": [
    "4776.20000",
    "0.02510294"
  ],
  "v": [
    "4.85183508",
    "61.15237421"
  ],
  "p": [
    "4775.02293",
    "4767.92898"
  ],
  "t": [
    126,
    608
  ],
  "l": [
    "4756.70000",
    "4720.60000"
  ],
  "h": [
    "4780.00000",
    "4783.30000"
  ],
  "o": "4776.40000"
 }
 }
}

这是反序列化并尝试显示List a的第一个值的代码

    private async void GetKraken(object sender, RoutedEventArgs e)
    {
        var client = new RestClient();
        IRestResponse response;
        Ticker BTCCADTicker = new Ticker();
        client.BaseUrl = new Uri("https://api.kraken.com/0/public/Ticker?pair=XBTCAD");
        var request = new RestRequest();
        response = await client.ExecuteTaskAsync(request);
        BTCCADTicker = JsonConvert.DeserializeObject<Ticker>(response.Content);
        MessageBox.Show(BTCCADTicker.result.XBTCAD.a[0]);
    }

我希望看到返回一个大约4700的值，但是我得到了上面的错误。是什么赋予了？任何帮助表示赞赏。

Answer 1

您尚未在模型中定义XXBTZCAD。您误将其称为XBTCAD。修复它看起来像这样：

public class Ticker
{
    public List<object> error { get; set; }
    public Result result { get; set; }

    public class Result
    {
        public XXBTZCAD XXBTZCAD { get; set; }


        public class XXBTZCAD
        {
            public List<string> a { get; set; }
            public List<string> b { get; set; }
            public List<string> c { get; set; }
            public List<string> v { get; set; }
            public List<string> p { get; set; }
            public List<int> t { get; set; }
            public List<string> l { get; set; }
            public List<string> h { get; set; }
            public string o { get; set; }
        }
    }
}

我现在看到的是与嵌套类相同的名称。我建议不要嵌套类的简单解决方案：

public class Ticker
{
    public List<object> error { get; set; }
    public Result result { get; set; }
}

public class Result
{
    public XXBTZCAD XXBTZCAD { get; set; }
}



public class XXBTZCAD
{
    public List<string> a { get; set; }
    public List<string> b { get; set; }
    public List<string> c { get; set; }
    public List<string> v { get; set; }
    public List<string> p { get; set; }
    public List<int> t { get; set; }
    public List<string> l { get; set; }
    public List<string> h { get; set; }
    public string o { get; set; }
}

如果您确实要嵌套它们，只需将class XXBTZCAD重命名为其他名称。对于反序列化而言，重要的是属性名称，而不是类型名称。

Answer 2

我建议在Visual Studio中复制您的JSON：

编辑>选择性粘贴>将JSON解析为类

public class Ticker
{
    public object[] error { get; set; }
    public Result result { get; set; }
}

public class Result
{
    public XXBTZCAD XXBTZCAD { get; set; }
}

public class XXBTZCAD
{
    public string[] a { get; set; }
    public string[] b { get; set; }
    public string[] c { get; set; }
    public string[] v { get; set; }
    public string[] p { get; set; }
    public int[] t { get; set; }
    public string[] l { get; set; }
    public string[] h { get; set; }
    public string o { get; set; }
}

，您可以使用此方法获取结果：

public static async Task<string> GetKraken()
{
    HttpClient client = new HttpClient();
    HttpResponseMessage response = await client.GetAsync("https://api.kraken.com/0/public/Ticker?pair=XBTCAD");
    response.EnsureSuccessStatusCode();
    string responseBody = await response.Content.ReadAsStringAsync();
    return responseBody;
}

然后使用该方法并将其转换为实际对象：

var ticker = JsonConvert.DeserializeObject<Ticker>(GetKraken().Result);

无法从嵌套的json

2 个答案: