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[英]How to get value of object inside object using System.Text.Json in .net core 3.1
[英]Is there a more elegant way to get specific value from JSON object using system.text.json
考虑这个 Json object:
{
"main": {
"2058": {
"id": "2058",
"name": "foo",
"attrib1": "17",
"domain": "somewhere.net",
"enabled": "1",
"permissions": [
"admin",
"user",
"guest",
"vpn",
"power"
]
}
},
"validate": {
"2058": {
"id": "2058",
"name": "foo",
"attrib1": "17",
"domain": "somewhere.net",
"enabled": "1",
"permissions": [
"admin",
"user",
"guest",
"vpn",
"power"
]
}
},
"result": "ok"
}
在“启用”和“权限”之间,我遗漏了数百对。 “验证”部分是“主要”的精确副本,“结果”是结果。
我想从主要部分获得 2 个特定值。 “id”和“域”。 我使用下面的代码来做到这一点。
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.Json;
namespace JsonParse
{
class Program
{
static void Main()
{
string json = "{" +
"\"main\":{" +
"\"2058\":{" +
"\"id\":\"2058\"," +
"\"name\":\"foo\"," +
"\"attrib1\":\"17\"," +
"\"domain\":\"somewhere.net\"," +
"\"enabled\":\"1\"," +
"\"permissions\":[\"admin\",\"user\",\"guest\",\"vpn\",\"power\"]" +
"}" +
"}," +
"\"validate\":{" +
"\"2058\":{" +
"\"id\":\"2058\"," +
"\"name\":\"foo\"," +
"\"attrib1\":\"17\"," +
"\"domain\":\"somewhere.net\"," +
"\"enabled\":\"1\"," +
"\"permissions\":[\"admin\",\"user\",\"guest\",\"vpn\",\"power\"]" +
"}" +
"}," +
"\"result\":\"ok\"" +
"}";
foreach (KeyValuePair<string, object> item in JsonSerializer.Deserialize<Dictionary<string, object>>(json))
{
if (item.Key == "main")
{
Dictionary<string, object> pairs = JsonSerializer.Deserialize<Dictionary<string, object>>(item.Value.ToString());
Dictionary<string, object> pairs1 = JsonSerializer.Deserialize<Dictionary<string, object>>(pairs.First().Value.ToString());
foreach (KeyValuePair<string, object> valuePair in pairs1)
{
if (valuePair.Key == "id" || valuePair.Key == "domain")
{
Console.WriteLine("Key: " + valuePair.Key + "\nValue: " + valuePair.Value);
}
}
}
}
}
}
}
由此,我得到“2058”和“somewhere.net”,但是有没有更优雅的方式来获取值而不是反序列化 3 次?
如果您使用System.Text.Json
API,则可以先将 JSON 解析为JsonDocument
,然后枚举其属性。 先获取main
object,然后将其子属性展平,通过id
和domain
找到需要的值
using var document = JsonDocument.Parse(jsonString);
var main = document.RootElement.EnumerateObject().FirstOrDefault(p => p.Name == "main");
var properties = main.Value.EnumerateObject().SelectMany(p => p.Value.EnumerateObject()).ToList();
var id = properties.FirstOrDefault(p => p.Name == "id").Value.GetString();
var domain = properties.FirstOrDefault(p => p.Name == "domain").Value.GetString();
如果您只需要main
属性,您可以通过 Newtonsoft Json.NET 使用json 路径到 select 所有“电源”:
var pairs = JObject.Parse(js).SelectTokens("$.main.*")
.Select(j => (id:j["id"],domain: j["domain"]))
.ToList();
或者只是反序列化为相应的结构(使用System.Text.Json
或 Newtonsoft):
class MyClass
{
public Dictionary<string, InnerClass> main { get; set; }
}
class InnerClass
{
public string id { get; set; }
public string domain { get; set; }
}
ICollection<InnerClass> mains= JsonSerializer.Deserialize<MyClass>(js).main.Values; // System.Text.Json
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