如何将 class 字段与 System.Text.Json.JsonSerializer 一起使用？

Question

我最近将一个解决方案升级为所有 .NET Core 3，并且我有一个 class 需要 class 变量作为字段。这是一个问题，因为新的 System.Text.Json.JsonSerializer 不支持序列化或反序列化字段，而是只处理属性。

有什么方法可以确保下面示例中的两个最终 class 具有完全相同的值吗？

using System.Text.Json;

public class Car
{
    public int Year { get; set; } // does serialize correctly
    public string Model; // doesn't serialize correctly
}

static void Problem() {
    Car car = new Car()
    {
        Model = "Fit",
        Year = 2008,
    };
    string json = JsonSerializer.Serialize(car); // {"Year":2008}
    Car carDeserialized = JsonSerializer.Deserialize<Car>(json);

    Console.WriteLine(carDeserialized.Model); // null!
}

Answer 1

在.NET Core 3.x中，System.Text.Json不序列化字段。来自 docs:

Fields are not supported in System.Text.Json in .NET Core 3.1. Custom converters can provide this functionality.

在 .NET 5 及更高版本中，可以通过设置 JsonSerializerOptions.IncludeFields to true or by marking the field to serialize with [JsonInclude]:

来序列化 public 字段

using System.Text.Json;

static void Main()
{
    var car = new Car { Model = "Fit", Year = 2008 };

    // Enable support
    var options = new JsonSerializerOptions { IncludeFields = true };

    // Pass "options"
    var json = JsonSerializer.Serialize(car, options);

    // Pass "options"
    var carDeserialized = JsonSerializer.Deserialize<Car>(json, options);

    Console.WriteLine(carDeserialized.Model); // Writes "Fit"
}

public class Car
{
    public int Year { get; set; }
    public string Model;
}

详情见：

How to serialize and deserialize (marshal and unmarshal) JSON in .NET: Include fields.
问题#34558 and #876。

Answer 2

请试试我写的这个库作为 System.Text.Json 的扩展来提供缺少的功能：https://github.com/dahomey-technologies/Dahomey.Json.

您会发现对字段的支持。

using System.Text.Json;
using Dahomey.Json

public class Car
{
    public int Year { get; set; } // does serialize correctly
    public string Model; // will serialize correctly
}

static void Problem() {
    JsonSerializerOptions options = new JsonSerializerOptions();
    options.SetupExtensions(); // extension method to setup Dahomey.Json extensions

    Car car = new Car()
    {
        Model = "Fit",
        Year = 2008,
    };
    string json = JsonSerializer.Serialize(car, options); // {"Year":2008,"Model":"Fit"}
    Car carDeserialized = JsonSerializer.Deserialize<Car>(json);

    Console.WriteLine(carDeserialized.Model); // Fit
}

如何将 class 字段与 System.Text.Json.JsonSerializer 一起使用？

How to use class fields with System.Text.Json.JsonSerializer?

c#

json.net

.net-core-3.0

system.text.json