C# 从最后一个 JSON 对象迭代到第一个

Question

有没有一种好方法可以从最后一个到第一个遍历反序列化的 JSON 对象？即，以下代码我可以从第一个到最后一个迭代并记录“n”个值，直到它满足我的计数条件以进行进一步处理：

protected void testButton_Click(object sender, EventArgs e)
    {

        List<decimal> priceHistory = new List<decimal>();

        
        var client = new RestClient("https://api.tdameritrade.com/v1/marketdata/" + inputSymbol + "/pricehistory?periodType=year&period=1&frequencyType=daily&frequency=1&needExtendedHoursData=false");
        client.Timeout = -1;
        var request = new RestRequest(Method.GET);
        request.AddHeader("Authorization", "Bearer " + ReadAccessToken());
        request.AddParameter("text/plain", "", ParameterType.RequestBody);
        IRestResponse response = client.Execute(request);

        dynamic history = JsonConvert.DeserializeObject<JObject>(response.Content);    

        int count = 0;    

        foreach (var child in history["candles"])
        {
            count += 1;

            while (count <= 100)
            {
                decimal close = child["close"];
                priceHistory.Add(close);
                break; 
            }
        }    

        decimal simpleMovingAverage = priceHistory.Average();

        responseLabel.Text = simpleMovingAverage.ToString();
      
        //output is taking the first 100 close prices returned from the JSON response and averaging those values. 

    }

但是，我找不到解决方案是如何从最后一个嵌套的 JSON 对象开始并从后到前的样式添加值。我试图将聚合从计算第一个嵌套对象 + 'n' 下一个值顺序到列表中的前一个值，到实际取响应中的最后一个嵌套 JSON 对象并将其与之前的每个 'n' 值取平均值，直到计数条件已经满足。

编辑

带有任意 'n' 句点的 JSON 示例供参考：

{
  "candles": [
    {
      "open": 172.51,
      "high": 176.36,
      "low": 171.5,
      "close": 171.86,
      "volume": 2292877,
      "datetime": 1582524000000
    },
    {
      "open": 172.18,
      "high": 172.945,
      "low": 165.8,
      "close": 166.65,
      "volume": 2358560,
      "datetime": 1582610400000
    },
    {
      "open": 168.28,
      "high": 169.38,
      "low": 165.61,
      "close": 166.92,
      "volume": 2545782,
      "datetime": 1582696800000
    },
    {
      "open": 164.4,
      "high": 166.55,
      "low": 159.96,
      "close": 159.99,
      "volume": 2957507,
      "datetime": 1582783200000
    },
    {
      "open": 155.29,
      "high": 158.92,
      "low": 152.66,
      "close": 156.48,
      "volume": 3053876,
      "datetime": 1582869600000
    },
    {
      "open": 157.92,
      "high": 164.0,
      "low": 156.55,
      "close": 163.92,
      "volume": 2532128,
      "datetime": 1583128800000
    }
  ],
  "symbol": "DE",
  "empty": false
}

Answer 1

您可以使用JArray 类的Reverse() 方法。只需将您的 history["candles"] JToken 转换为 JArray，然后调用 reverse。

void ParseJson(string json)
{
    var history = JObject.Parse(json);
    var candles = (history["candles"] as JArray).Reverse();

    foreach (var child in candles)
    {
        Console.WriteLine(child["close"].ToString());
    }

    Console.Read();
}