Question

我有一个文本文件，其中包含近百万条json格式的记录。像

[{"ev":"AM","sym":"TMHC","v":1000,"av":74917,"op":18.92,"vw":19.1305,"o":19.13,"c":19.15,"h":19.15,"l":19.13,"a":19.143,"z":90,"n":1,"s":1549380300000,"e":1549380360000},{"ev":"AM","sym":"AAPL","v":7103,"av":184266,"op":35.27,"vw":35.3148,"o":35.3264,"c":35.34,"h":35.34,"l":35.3258,"a":35.3345,"z":710,"n":1,"s":1549380300000,"e":1549380360000}]
[{"ev":"AM","sym":"VB","v":213,"av":98285,"op":149.75,"vw":150.0575,"o":150.2104,"c":150.2104,"h":150.2104,"l":150.2104,"a":150.1944,"z":35,"n":1,"s":1549380300000,"e":1549380360000}]

所以我需要从包含AAPL的文件中找到json元素列表。就像我要通过AAPL一样，它必须提供整个文件中AAPL的json元素列表。

{"ev":"AM","sym":"AAPL","v":7103,"av":184266,"op":35.27,"vw":35.3148,"o":35.3264,"c":35.34,"h":35.34,"l":35.3258,"a":35.3345,"z":710,"n":1,"s":1549380300000,"e":1549380360000}

那我怎么找到它呢？我正在尝试为此使用JSONPATH，但是在JObject转换时，它给出了

之类的错误

从JsonReader读取JObject时出错

我已为其应用以下代码：

const string filePath = @"D:\Aggregate_Minute_AAPL.json";
string text = System.IO.File.ReadAllText(filePath);
Newtonsoft.Json.Linq.JArray jsonArray = Newtonsoft.Json.Linq.JArray.Parse(text);
var json = Newtonsoft.Json.Linq.JObject.Parse(jsonArray.ToString());
var title = json.SelectToken("$.ev.sym[*]");
Console.WriteLine(title.First());

Answer 1

您需要获取所有数组，而不管它们是全部还是一行，或者每个数组都位于换行符上，然后将每个数组解析为implementation 'androidx.core:core-ktx:1.0.1' implementation 'androidx.appcompat:appcompat:1.0.2'，然后使用所需键找到属性并获取该键的相应对象

JArray

用法：

public static List<JObject> GetObjectByValue(string filePath, string matchValue)
{
    var text = File.ReadAllText(filePath);

    var pattern = @"\[(.*?)\]";

    var matches = Regex.Matches(text, pattern);

    var result = matches.Cast<Match>()
            .Select(a => JArray.Parse(a.Value))
            .Select(b => b.ToObject<JObject[]>())
            .Where(x => x.Properties()
                         .Any(y => y.Name == "sym" && y.Value.ToString() == matchValue))
                         .FirstOrDefault()
            .ToList();

    return result;
}

编辑1：

如果您想使用var list_obj = GetObjectByValue(@"Path to your text file", "VB");获取匹配对象，则可以使用以下函数，

Parallel.For

Answer 2

由于文件很大，因此最好逐行读取而不是一次读取。

了解您的结构：每一行都是一个JSON数组，并且该数组有一个JSON对象。

// reading lines in loop
foreach (var line in System.IO.File.ReadLines(filePath))
{
    // Parse the line into the array
    JArray jsonArray = Newtonsoft.Json.Linq.JArray.Parse(line);
    //parse the array into object, 
    //since each line has one object I have hardcoded the index to 0
    //if there can be more objects in one array then will need to iterate
    var json = JObject.Parse(jsonArray[0].ToString());
    // access the token
    var title = json["sym"]; // or json.SelectToken("sym");
    Console.WriteLine(title.First());
}

如何从txt文件中查找特定的json元素数据列表？

2 个答案: