Question

我想将动态对象转换为json字符串。当我过去使用Newtonsoft.Json时，它工作得非常完美。当我将.net core升级到3.0并使用System.Text.Json时，这很糟糕。

查看代码：

using System;
using System.Collections.Generic;
using System.Dynamic;
namespace ConsoleApp
{
    class Program
    {
        static void Main(string[] args)
        {
            dynamic product = new ExpandoObject();
            product.ProductName = "Elbow Grease";
            product.Enabled = true;
            product.Price = 4.90m;
            product.StockCount = 9000;
            product.StockValue = 44100;
            product.Tags = new string[] { "Real", "OnSale" };

            // Will output: { "ProductName":"Elbow Grease","Enabled":true,"Price":4.90,
            // "StockCount":9000,"StockValue":44100,"Tags":["Real","OnSale"]}
            var json1 = Newtonsoft.Json.JsonConvert.SerializeObject(product);
            Console.WriteLine(json1);

            // Both will throw exception: System.InvalidCastException:“Unable to
            // cast object of type '<GetExpandoEnumerator>d__51' to type
            // 'System.Collections.IDictionaryEnumerator'.”
            var json2 = System.Text.Json.JsonSerializer.Serialize(product);
            Console.WriteLine(json2);
            var json3 = System.Text.Json.JsonSerializer.Serialize<IDictionary<string, object>>(product as IDictionary<string, object>);
            Console.WriteLine(json3);

            Console.ReadKey();
        }
    }
}

如果我想继续使用System.Text.Json转换动态对象，因为我听说它比其他json转换快，那我该怎么办？

Answer 1

此记录为JsonSerializer support for ExpandoObject #38007 stil截至2019年10月21日开放。

您可以改用匿名类型。

var product = new {
            ProductName = "Elbow Grease",
            Enabled = true,
            Price = 4.90m,
            StockCount = 9000,
            StockValue = 44100,
            Tags = new string[] { "Real", "OnSale" }
        };


var json1 = Newtonsoft.Json.JsonConvert.SerializeObject(product);
Console.WriteLine(json1);

var json2 = System.Text.Json.JsonSerializer.Serialize(product);
Console.WriteLine(json2);

{"ProductName":"Elbow Grease","Enabled":true,"Price":4.90,"StockCount":9000,"StockValue":44100,"Tags":["Real","OnSale"]}
{"ProductName":"Elbow Grease","Enabled":true,"Price":4.90,"StockCount":9000,"StockValue":44100,"Tags":["Real","OnSale"]}

使用System.Text.Json.Serialization将动态对象转换为json时引发异常

1 个答案: