C# 去除JSON的空节点

方法一：

using Newtonsoft.Json.Linq;
using System;
using System.Collections.Generic;
using System.Linq;

JObject testJson = new JObject()
{
    { "code", "1234560" },
    { "app", null }
};
testJson.DescendantsAndSelf()
        .OfType<JProperty>()
        .Where(p => p.Value.Type == JTokenType.Null || p.Value.ToString() == "")
        .ToList()
        .ForEach(p => p.Remove());

方法二：

直接调用方法即可

private static void RemoveEmptyValues(JToken token)
{
    if (token is JValue)
    {
        if (token.Type == JTokenType.Null || (token.Type == JTokenType.String && token.ToString() == ""))
        {
            token.Parent.Remove();
        }
    }
    else if (token is JContainer)
    {
        foreach (JToken child in token.Children().ToList())
        {
            RemoveEmptyValues(child);
        }

        if (!token.HasValues)
        {
            token.Parent.Remove();
        }
    }
}

方法三：

直接调用方法即可

public static JToken RemoveEmptyValues(JToken token)
{
    if (token.Type == JTokenType.Object)
    {
        JObject obj = (JObject)token;
        List<string> keysToRemove = new List<string>();
        foreach (JProperty prop in obj.Properties())
        {
            JToken propValue = RemoveEmptyValues(prop.Value);
            if (propValue.Type == JTokenType.Null ||
                propValue.Type == JTokenType.String && ((string)propValue).Trim() == "" ||
                propValue.Type == JTokenType.Array && !propValue.HasValues ||
                propValue.Type == JTokenType.Object && !((JObject)propValue).HasValues)
            {
                keysToRemove.Add(prop.Name);
            }
            else
            {
                prop.Value = propValue;
            }
        }

        foreach (string key in keysToRemove)
        {
            obj.Remove(key);
        }

        return obj;
    }
    else if (token.Type == JTokenType.Array)
    {
        JArray arr = (JArray)token;
        List<JToken> itemsToRemove = new List<JToken>();
        for (int i = 0; i < arr.Count; i++)
        {
            JToken item = RemoveEmptyValues(arr[i]);
            if (item.Type == JTokenType.Null ||
                item.Type == JTokenType.String && ((string)item).Trim() == "" ||
                item.Type == JTokenType.Array && !item.HasValues ||
                item.Type == JTokenType.Object && !((JObject)item).HasValues)
            {
                itemsToRemove.Add(arr[i]);
            }
            else
            {
                arr[i] = item;
            }
        }

        foreach (JToken item in itemsToRemove)
        {
            arr.Remove(item);
            //item.RemoveFromLowestPossibleParent();
        }

        return arr;
    }

    // 对于其他类型的JToken（如原始值），直接返回原始token
    return token;
}

方法四：

仅针对于有对应实体类的JSON序列化

public class Person
{
    public string Name { get; set; }
    public int? Age { get; set; }
}

static void Main(string[] args)
{
  Person person = new Person()
  {
      Name = "Test",
      Age = null
  };
  var setting = new JsonSerializerSettings
  {
      NullValueHandling = NullValueHandling.Ignore
  };
  string str = JsonConvert.SerializeObject(person, setting); 
}