使用C#将HttpClient返回的嵌套JSON转换为指定扁平化结构

输入JSON结构 #

{"data": {"trafficData": {"volume": {"byHour": {"edges": [{"node": {"from": "2019-10-24T12:00:00+02:00","to": "2019-10-24T13:00:00+02:00","byDirection": [{"heading": "North","total": {"volumeNumbers": {"volume": 696}}},{"heading": "South","total": {"volumeNumbers": {"volume": 726}}}]}},{"node": {"from": "2019-10-24T13:00:00+02:00","to": "2019-10-24T14:00:00+02:00","byDirection": [{"heading": "North","total": {"volumeNumbers": {"volume": 805}}},{"heading": "South","total": {"volumeNumbers": {"volume": 751}}}]}}]}}}}}

目标JSON结构 #

{"data":[{"from":"2019-10-24T12:00:00+02:00","to":"2019-10-24T13:00:00+02:00","heading":"South","volume":726},{"from":"2019-10-24T13:00:00+02:00","to":"2019-10-24T14:00:00+02:00","heading":"South","volume":751}]}

现有尝试代码 #

// o1 is the json object input
IEnumerable<JToken> jTokens = o1.Descendants().Where(p => !p.HasValues);
Dictionary<string, string> results = jTokens.Aggregate(new Dictionary<string, string>(), (properties, jToken) =>
{
    properties.Add(jToken.Path, jToken.ToString());
    return properties;
});

可行转换方案 #

方案一：LINQ to JSON（Newtonsoft.Json）直接处理

无需定义完整类，适合快速转换：

using Newtonsoft.Json;
using Newtonsoft.Json.Linq;

// o1为已解析的JObject
var edges = o1.SelectToken("data.trafficData.volume.byHour.edges") as JArray;

var transformedItems = edges
    .SelectMany(edge => 
    {
        var node = edge["node"];
        var from = node["from"].ToString();
        var to = node["to"].ToString();
        
        // 筛选South方向数据
        return node["byDirection"]
            .Where(dir => dir["heading"].Value<string>() == "South")
            .Select(dir => new 
            {
                from = from,
                to = to,
                heading = dir["heading"].Value<string>(),
                volume = dir["total"]["volumeNumbers"]["volume"].Value<int>()
            });
    })
    .ToList();

var resultJson = JsonConvert.SerializeObject(new { data = transformedItems });

方案二：强类型序列化转换

先定义对应类（可通过json2csharp生成），再完成类型转换：

定义类：

// 输入结构类
public class InputRoot
{
    public Data Data { get; set; }
}

public class Data
{
    public TrafficData TrafficData { get; set; }
}

public class TrafficData
{
    public Volume Volume { get; set; }
}

public class Volume
{
    public ByHour ByHour { get; set; }
}

public class ByHour
{
    public List<Edge> Edges { get; set; }
}

public class Edge
{
    public Node Node { get; set; }
}

public class Node
{
    public string From { get; set; }
    public string To { get; set; }
    public List<ByDirection> ByDirection { get; set; }
}

public class ByDirection
{
    public string Heading { get; set; }
    public Total Total { get; set; }
}

public class Total
{
    public VolumeNumbers VolumeNumbers { get; set; }
}

public class VolumeNumbers
{
    public int Volume { get; set; }
}

// 目标结构类
public class TargetItem
{
    public string from { get; set; }
    public string to { get; set; }
    public string heading { get; set; }
    public int volume { get; set; }
}

public class TargetRoot
{
    public List<TargetItem> data { get; set; }
}

转换代码：

using Newtonsoft.Json;

// 解析输入JSON到强类型对象
var input = JsonConvert.DeserializeObject<InputRoot>(inputJson);

var targetItems = input.Data.TrafficData.Volume.ByHour.Edges
    .SelectMany(edge => 
        edge.Node.ByDirection
            .Where(dir => dir.Heading == "South")
            .Select(dir => new TargetItem
            {
                from = edge.Node.From,
                to = edge.Node.To,
                heading = dir.Heading,
                volume = dir.Total.VolumeNumbers.Volume
            })
    )
    .ToList();

var resultJson = JsonConvert.SerializeObject(new TargetRoot { data = targetItems });

两种方案均能实现需求：方案一适合临时、快速转换场景；方案二更适合需要类型安全、多次复用的业务场景。

内容的提问来源于stack exchange，提问作者user19876549