c# - 读取 json 对象并找到其中的值

Question

我有以下 GET 请求:

string url = @"http://api.flexianalysis.com/services/flexianalysisservice.svc/TechnicalAnalysisByCategory?clientid=___&category=forex&key=____";

        HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
        request.AutomaticDecompression = DecompressionMethods.GZip;

        using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
        using (Stream stream = response.GetResponseStream())
        using (StreamReader reader = new StreamReader(stream))
        {
             rawJson = new StreamReader(response.GetResponseStream()).ReadToEnd();
            //html = reader.ReadToEnd();
        }

这是 JSON 的示例:

[{"ID":133739,"TickerID":23,"CategoryID":3,"ClientID":5044,"TickerDateTime":"2017-11-06T12:57:19.267","TickerTitle":"AUD/USD Intraday: key resistance at 0.7670.\r\n","Category":"Forex","TradePairName":"AUD/USD","Ticker":"AUD","TrendType":"THE upside prevails","Status":"Enabled","TrendValue1":"+1","PivotValue":0.767,"OurPreference":"v: short positions below 0.7670 with targets at 0.7635 & 0.7615 in extension.\r\n","AlternateScenario":"o: above 0.7670 look for further upside with 0.7695 & 0.7715 as targets.\r\n","Comments":" as long as 0.7670 is resistance, look for choppy price action with a bearish bias.\r\n","S1":0.7635,"S2":0.7615,"S3":0.7595,"R1":0.767,"R2":0.7695,"R3":0.7715,"Entry":0.0,"Stop":0.0,"T1":0.0,"T2":0.0},{"ID":133738,"TickerID":193,"CategoryID":3,"ClientID":5044,"TickerDateTime":"2017-11-06T12:55:54.33","TickerTitle":"Dollar Index‏ (ICE) Intraday: bullish bias above 94.8000.\r\n","Category":"Forex","TradePairName":"Dollar Index (ICE)","Ticker":"DXA","TrendType":"THE upside prevails","Status":"Enabled","TrendValue1":"+1""PivotValue":94.8,"OurPreference":": long positions above 94.8000 with targets at 95.1500 & 95.3000 in extension.\r\n","AlternateScenario":"below 94.8000 look for further downside with 94.6500 & 94.4500 as targets.\r\n","Comments":": the RSI lacks downward momentum.","S1":94.8,"S2":94.65,"S3":94.45,"R1":95.15,"R2":95.3,"R3":95.45,"Entry":0.0,"Stop":0.0,"T1":0.0,"T2":0.0}]

然后我尝试将其解析为 JSON 并删除开头的“d”:

var json = JObject.Parse(rawJson);
        var filter = json["d"];
        var fff = filter["ID"];//Get the error here

现在我想读取 ID，但由于某种原因它给出了无法访问子节点的错误。知道为什么吗？

Answer 1

我认为您需要检查一些假设并尝试一些断点。

查看该 API 返回的 JSON，它看起来格式不正确，您实际上收到的是 JSON 数组作为字符串:

{"d":"[{\"ID\":133739,\"TickerID\":23,\"CategoryID\":3,...}},
       {\"ID\":133740,\"TickerID\":23,\"CategoryID\":3,...}},
       [...]}]"}

因此要解析它，您首先需要从 d 参数中获取值，然后将其解析为一个数组:

// Get the response from the server
using (HttpWebResponse response = (HttpWebResponse) request.GetResponse())
{
    // Pass the response into a stream reader
    using (StreamReader reader = new StreamReader(response.GetResponseStream()))
    {
        // Grab the JSON response as a string
        string rawJson = reader.ReadToEnd();

        // Parse the string into a JObject
        var json = JObject.Parse(rawJson);

        // Get the JToken representing the ASP.NET "d" parameter
        var d = json.GetValue("d");

        // Parse the string value of the object into a jArray
        var jArray = JArray.Parse(d.ToString());

        // At this point you can start looking for the items.
    }
}