Trouble deserializing JSON to a C# object

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英文:

Trouble deserializing JSON to a C# object

问题

我正在开发一个WPF MVVM应用程序，用于从此API获取一些加密货币信息。我能够调用API并获得HTTP响应，但我在将此响应反序列化为对象时遇到了问题。我理解传递了符号变量但未使用它，但我希望反序列化过程能够正常运行，然后我将相应地格式化URI以包含符号和API密钥。以下是代码：

Crypto对象

  1. public class Crypto
  2. {
  3.     public string? Symbol { get; set; }
  4.     public string? Name { get; set; }
  5.     public double? Price { get; set; }
  6.     public double? ChangesPercentage { get; set; }
  7. }

API调用服务接口

  1. public interface ICryptoService
  2. {
  3.     Task<Crypto> GetCrypto(string symbol); 
  4. }

API调用服务

  1. public async Task<Crypto> GetCrypto(string symbol)
  2. {
  3.     using (HttpClient client = new HttpClient())
  4.     {
  5.         using var response = await client.GetAsync("https://financialmodelingprep.com/api/v3/quote/BTCUSD?apikey=KEY", HttpCompletionOption.ResponseHeadersRead);
  7.         response.EnsureSuccessStatusCode();
  9.         if (response.Content is object && response.Content.Headers.ContentType.MediaType == "application/json")
  10.         {
  11.             var responseStream = await response.Content.ReadAsStreamAsync();
  13.             try
  14.             {
  15.                 return await System.Text.Json.JsonSerializer.DeserializeAsync<Crypto>(responseStream, new System.Text.Json.JsonSerializerOptions { IgnoreNullValues = true, PropertyNameCaseInsensitive = true });
  16.             }
  17.             catch (JsonException)
  18.             {
  19.                 Console.WriteLine("Invalid JSON!");
  20.             }
  21.         }
  22.         else
  23.         {
  24.             Console.WriteLine("HTTP Response cannot be deserialised");
  25.         }
  27.         return null;
  28.     }
  29. }

主方法

  1. CryptoService cryptoService = new CryptoService();
  3. cryptoService.GetCrypto("BTCUSD").ContinueWith((task) =>
  4. {
  5.     var crypto = task.Result;
  6. });

我附上了链接将提供的JSON响应：

  1. [
  2.  {
  3.     "symbol": "BTCUSD",
  4.     "name": "Bitcoin USD",
  5.     "price": 22887.08,
  6.     "changesPercentage": -0.1263,
  7.     "change": -28.9473,
  8.     "dayLow": 22887.08,
  9.     "dayHigh": 23351.51,
  10.     "yearHigh": 48086.836,
  11.     "yearLow": 15599.047,
  12.     "marketCap": 441375461059,
  13.     "priceAvg50": 19835.04,
  14.     "priceAvg200": 19730.518,
  15.     "volume": 27292504064,
  16.     "avgVolume": 23965132574,
  17.     "exchange": "CRYPTO",
  18.     "open": 23267.4,
  19.     "previousClose": 23267.4,
  20.     "eps": null,
  21.     "pe": null,
  22.     "earningsAnnouncement": null,
  23.     "sharesOutstanding": 19284918,
  24.     "timestamp": 1675872360
  25.  }
  26. ]

这是我运行代码时遇到的异常：

  1. Exception thrown: 'System.Text.Json.JsonException' in System.Private.CoreLib.dll
英文:

I am working on a WPF MVVM application to retrieve some cryptocurrency information from this API. I am able to call the API and get an HTTP response, however, I am having trouble deserializing this response to an object. I understand that the symbol variable is passed but not used, however, I want the deserialization process to work and then I will format the URI accordingly to include the symbol and the API Key. Here is the code:

Crypto Object

  1. public class Crypto
  2. {
  3.     public string? Symbol { get; set; }
  4.     public string? Name { get; set; }
  5.     public double? Price { get; set; }
  6.     public double? ChangesPercentage { get; set; }
  7. }

API Call Service Interface

  1. public interface ICryptoService
  2. {
  3.     Task&lt;Crypto&gt; GetCrypto(string symbol); 
  4. }

API Call Service

  1. public async Task&lt;Crypto&gt; GetCrypto(string symbol)
  2.     {
  3.         using (HttpClient client = new HttpClient())
  4.         {
  5.             using var response = await client.GetAsync(&quot;https://financialmodelingprep.com/api/v3/quote/BTCUSD?apikey=KEY&quot;, HttpCompletionOption.ResponseHeadersRead);
  7.             response.EnsureSuccessStatusCode();
  9.             if (response.Content is object &amp;&amp; response.Content.Headers.ContentType.MediaType == &quot;application/json&quot;)
  10.             {
  11.                 var responseStream = await response.Content.ReadAsStreamAsync();
  13.                 try
  14.                 {
  15.                     return await System.Text.Json.JsonSerializer.DeserializeAsync&lt;Crypto&gt;(responseStream, new System.Text.Json.JsonSerializerOptions { IgnoreNullValues = true, PropertyNameCaseInsensitive = true });
  16.                 }
  17.                 catch (JsonException)
  18.                 {
  19.                     Console.WriteLine(&quot;Invalid JSON!&quot;);
  20.                 }
  21.             }
  22.             else
  23.             {
  24.                 Console.WriteLine(&quot;HTTP Response cannot be deserialised&quot;);
  25.             }
  27.             return null;
  28.         }
  29.     }
  30. }

Main Method

  1.         CryptoService cryptoService = new CryptoService();
  3.         cryptoService.GetCrypto(&quot;BTCUSD&quot;).ContinueWith((task) =&gt;
  4.         {
  5.             var crypto = task.Result;
  6.         });

I am attaching the JSON response that the link will provide below:

  1. [
  2.  {
  3. &quot;symbol&quot;: &quot;BTCUSD&quot;,
  4. &quot;name&quot;: &quot;Bitcoin USD&quot;,
  5. &quot;price&quot;: 22887.08,
  6. &quot;changesPercentage&quot;: -0.1263,
  7. &quot;change&quot;: -28.9473,
  8. &quot;dayLow&quot;: 22887.08,
  9. &quot;dayHigh&quot;: 23351.51,
  10. &quot;yearHigh&quot;: 48086.836,
  11. &quot;yearLow&quot;: 15599.047,
  12. &quot;marketCap&quot;: 441375461059,
  13. &quot;priceAvg50&quot;: 19835.04,
  14. &quot;priceAvg200&quot;: 19730.518,
  15. &quot;volume&quot;: 27292504064,
  16. &quot;avgVolume&quot;: 23965132574,
  17. &quot;exchange&quot;: &quot;CRYPTO&quot;,
  18. &quot;open&quot;: 23267.4,
  19. &quot;previousClose&quot;: 23267.4,
  20. &quot;eps&quot;: null,
  21. &quot;pe&quot;: null,
  22. &quot;earningsAnnouncement&quot;: null,
  23. &quot;sharesOutstanding&quot;: 19284918,
  24. &quot;timestamp&quot;: 1675872360
  25.  }
  26. ]

This is the exception that I get whenever I run the code:

  1. Exception thrown: &#39;System.Text.Json.JsonException&#39; in System.Private.CoreLib.dll

答案1

得分: 1

你的 JSON 是一个 JSON 数组，而不是一个单独的 JSON 对象，因此你需要反序列化为一个集合：

  1. var result = await JsonSerializer.DeserializeAsync&lt;List&lt;Crypto&gt;&gt;(...);

P.S.

通常情况下，建议只使用 await 异步函数，而不是使用 ContinueWith。

英文:

Your json is a json array, not a single json object, so you need to deserialize to a collection:

  1. var result = await JsonSerializer.DeserializeAsync&lt;List&lt;Crypto&gt;&gt;(...);

P.S.

In general case it is recommended to just await async functions instead of using ContinueWith.

huangapple
  • 本文由 发表于 2023年2月9日 02:33:00
  • 转载请务必保留本文链接：https://go.coder-hub.com/75390281.html
  • c#
  • json
  • system.text.json
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