c# 从 json 中获取值

Question

我有一个 json 文本，我想获取作者姓名和描述标签的值。不需要其他字段，如 url 和 urltoimage 等等。当我运行以下代码时，不提供任何字符串值。我认为这里有一些错误。

{
  "status": "ok",
  "articles": [
  {
    "source": {
      "id": "techcrunch",
      "name": "TechCrunch"
    },
    "author": "Khaled \"Tito\" Hamze",
    "title": "Crunch Report",
    "description": "Your daily roundup of the biggest TechCrunch stories and startup news.",
    "url": "https://techcrunch.com/video/crunchreport/",
    "urlToImage": "https://tctechcrunch2011.files.wordpress.com/2015/03/tccrshowogo.jpg?w=500&h=200&crop=1",
    "publishedAt": "2017-12-11T20:20:09Z"
  },
  {
    "source": {
      "id": "techcrunch",
      "name": "TechCrunch"
    },
    "author": "Sarah Perez",
    "title": "Facebook is trying to make the Poke happen again",
    "description": "Facebook's \"Poke\" feature has never really gone away, but now the social network is giving it a more prominent placement - and is even considering expanding..",
    "url": "https://techcrunch.com/2017/12/11/facebook-is-trying-to-make-the-poke-happen-again/",
    "urlToImage": "https://tctechcrunch2011.files.wordpress.com/2017/12/facebook-poke-icon.jpg",
    "publishedAt": "2017-12-11T20:02:30Z"
  },
  {
    "source": {
      "id": "techcrunch",
      "name": "TechCrunch"
    },
    "author": "Sarah Perez",
    "title": "Amazon Alexa can now wake you up to music",
    "description": "This fall, Amazon made a play to become your new alarm clock with the introduction of a combination smart speaker and clock called the Echo Spot. Today, the..",
    "url": "https://techcrunch.com/2017/12/11/amazon-alexa-can-now-wake-you-up-to-music/",
    "urlToImage": "https://tctechcrunch2011.files.wordpress.com/2017/09/amazon-event-9270069.jpg",
    "publishedAt": "2017-12-11T17:22:30Z"
  },
  {
    "source": {
      "id": "techcrunch",
      "name": "TechCrunch"
    },
    "author": "Ingrid Lunden, Katie Roof",
    "title": "Apple confirms Shazam acquisition; Snap and Spotify also expressed interest",
    "description": "After we broke the story last week that Apple was acquiring London-based music and image recognition service Shazam, Apple confirmed the news today. It is..",
    "url": "https://techcrunch.com/2017/12/11/apple-shazam-deal/",
    "urlToImage": "https://tctechcrunch2011.files.wordpress.com/2017/12/shazam-app-icon-ios.jpg",
    "publishedAt": "2017-12-11T15:59:31Z"
  }
]}

如何得到这个？下面是我的代码，它根本不起作用

var data = (JObject)JsonConvert.DeserializeObject(myJSON);
string nameArticles= data["articles"].Value<string>();
MessageBox.Show(nameArticles);


   public class Source
   {
    public string id { get; set; }
    public string name { get; set; }
   }
   public class Article
   {
    public Source source { get; set; }
    public string author { get; set; }
    public string title { get; set; }
    public string description { get; set; }
    public string url { get; set; }
    public string urlToImage { get; set; }
    public DateTime publishedAt { get; set; }
   }

            Article art = new Article();

            art = JsonConvert.DeserializeObject<Article>(myJSON);

            MessageBox.Show(art.description.ToString());

上面的代码返回对象未设置为实例错误！

Answer 1

如果您不想创建包装类，您可以尝试下面的代码片段，它使用动态类型将JSON 反序列化为对象。

var json = "Your JSON string";

dynamic stuff = JsonConvert.DeserializeObject(json);

string name = stuff.status;
var arr = stuff.articles;

foreach (var a in arr)
{
   var authorName = a.author;
}

Answer 2

data["articles"] is likely to be a JArray not a string. You'll need to iterate over each JObject in the aforementioned JArray pulling out the author and description values

var data = (JObject)JsonConvert.DeserializeObject(myJSON);
var articles = data["articles"].Children();

foreach (var article in articles)
{
    var author = article["author"].Value<string>();
    var description = article["author"].Value<string>();

    Console.WriteLine($"Author: " + author + ", Description: " + description);
}

This should help you get started with whatever you're doing.

Answer 3

假设您希望反序列化为具体类（按照问题中显示的第二种尝试方法），那么您需要一个包装类来保存整个对象，并反序列化为该对象。

目前，您正在尝试将整个对象序列化为Article，但只有该对象数组中的各个对象articles才能与类中的结构匹配Article。

您试图在对象的错误级别执行操作，并且您忘记了它articles是一个列表（数组）这一事实。

像这样的东西：

public class JSONResponse
{
    public string status { get; set; }
    public List<Article> articles { get; set; }
}

和

JSONResponse response = JsonConvert.DeserializeObject<JSONResponse>(myJSON);

然后，您可以使用普通循环来迭代列表response.articles并提取作者姓名和描述。