将 API 中的 JSON 数据解析并过滤到 C# 应用程序中

Question

我的目标是从 "The virus tracker" API 检索 JSON 数据并将其解析为标签。这是我的 IB 个人项目，所以我刚开始学习 c#。找到这个旧代码并尝试修复它，它适用于基本的 GET API，但它不适用于我正在使用的代码。（英语不是我的主要语言）

邮递员回复

{
   "results": [
      {
         "total_cases": 5954607,
         "total_recovered": 2622507,
         "total_unresolved": 2255875,
         "total_deaths": 363208,
         "total_new_cases_today": 53700,
         "total_new_deaths_today": 1659,
         "total_active_cases": 45257,
         "total_serious_cases": 2698001,
         "total_affected_countries": 213,
         "source": {
            "url": "https://thevirustracker.com/"
         }
      }
   ],
   "stat": "ok"
}

C# 代码

//Creating Client connection 
        RestClient restClient = new RestClient("https://thevirustracker.com/free-api?global=stats");


        //Creating request to get data from server
        RestRequest restRequest = new RestRequest("total_cases", Method.GET);


        // Executing request to server and checking server response to the it
        IRestResponse restResponse = restClient.Execute(restRequest);


        // Extracting output data from received response
        string response = restResponse.Content;

        // Parsing JSON content into element-node JObject
        var jObject = JObject.Parse(restResponse.Content);

        //Extracting Node element using Getvalue method
        string cases = jObject.GetValue("total_cases").ToString();
        label1.Text = (cases);

错误

An unhandled exception of type 'Newtonsoft.Json.JsonReaderException' occurred in Newtonsoft.Json.dll
Unexpected character encountered while parsing value: <. Path '', line 0, position 0.

我使用此代码的最终目标是 label1 显示“5954607”

请记住，我对此很陌生，所以如果您能解释一下您对代码所做的更改，我将不胜感激。

Answer 1

您没有正确使用 RestRequest 或错误地初始化了 RestClient。

如果您在 RestClient 中使用的 url 是整个 url 那么您不需要在 RestRequest 中使用 "resource"。

由于这个错误，您得到了 HTML 错误指示的响应

Unexpected character encountered while parsing value: <. Path '', line 0, position 0.

restResponse.Content 的值可能以 <html 开头，那是无效的 JSON。

Json 有效载荷比您编码的要复杂一些。结果对象包含一个数组，其中包含一个包含您的统计数据的对象属性.

将这些修复放在一起就得到了这段代码。

RestClient restClient = new RestClient("https://thevirustracker.com/free-api?global=stats");

//Creating request to get data from server
RestRequest restRequest = new RestRequest(null, DataFormat.Json);

// Executing request to server and checking server response to the it
IRestResponse restResponse = restClient.Execute(restRequest);

// Extracting output data from received response
string response = restResponse.Content;

// Parsing JSON content into element-node JObject
var jObject = JObject.Parse(restResponse.Content);

//Extracting 
// the object has a results property 
// that is an array with one item (zero-based)
// on index 0 there is an object
// that has a property total_cases
string cases = (string) jObject["results"][0]["total_cases"];
label1.Text = (cases);

将 API 中的 JSON 数据解析并过滤到 C# 应用程序中

Parsing & Filtering JSON data from API into C# application

c#

json

restsharp