c# - JsonSerializer.Serialize 返回空对象

Question

我正在尝试将我创建的类的对象保存到文件中，但 JsonSerializer.Serialize 返回 {}。

class User : DalObject<User>
{
    private readonly log4net.ILog log = log4net.LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);
    private string email;
    private string nickname;
    private string password;
    private bool LoggedIn;

    public User(string email, string password, string nickname, bool LoggedIn)
    {
        this.email = email;
        this.password = password;
        this.nickname = nickname;
        this.LoggedIn = LoggedIn;
    }

    public string ToJson()
    {
        var options = new JsonSerializerOptions
        {
            WriteIndented = true
        };
        log.Debug("User " + this.email + " saved");
        return JsonSerializer.Serialize(this, options);
    }

Answer 1

JsonSerializer.Serialize只序列化公共(public)属性。您只有(私有(private))字段。

Serialization behavior

• By default, all public properties are serialized. You can specify properties to exclude.

• ...

• Currently, fields are excluded.

来自 Microsoft docs

可能自 .NET 5 以来

从 .NET 5 开始，可以包含字段。使用 JsonSerializerOptions.IncludeFields 全局设置或 [JsonInclude] 属性在序列化或反序列化时包含字段。

参见 https://learn.microsoft.com/en-us/dotnet/standard/serialization/system-text-json-how-to?pivots=dotnet-5-0#include-fields

解决 .NET 5 之前的问题

你可以使用 Json.NET并将 [JsonProperty] 添加到私有(private)字段。

Json.NET中的方法是JsonConvert.SerializeObject