如何防止被序列化整个类？ [英] How to prevent an entire class from being serialized?

问题描述

我使用Newtonsoft.Json来序列化一个类及其所有成员。有一个特定的类，它的许多成员是一个实例，我只想告诉一个类不进行序列化，所以如果任何成员是该类型的实例被跳过。

I am using Newtonsoft.Json to serialize a class and all of its members. There is one particular class that many of its members are an instance of, I'd simply like to tell a class to not be serialized at all, so if any member that is an instance of that type is skipped.

在C＃中，通过向类添加某种属性以将其标记为不可序列化，这是否可能？

Is this possible in C# by appending some sort of attribute to a class to mark it as non-serializable?

推荐答案

我不认为这可以使用类上的属性。但是你应该能够实现一个自定义的 JsonConverter ，它总是序列化和反序列化这个类的任何实例到 null 。这个代码实现了这样的行为：

I do not think this can be done using an attribute on the class. However you should be able to do it by implementing a custom JsonConverter which always serializes and deserializes any instance of this class to null. This code implements such behavior:

class IgnoringConverter : JsonConverter
{
    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        writer.WriteNull();
    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        return null;
    }

    public override bool CanConvert(Type objectType)
    {
        return objectType == typeof(ClassToIgnore);
    }
}

在此示例中， ClassToIgnore 是您希望在序列化期间忽略的类。这些类应该用 JsonConverter 属性进行修饰：

In this example, ClassToIgnore is the class you wish to ignore during serialization. Such classes should be decorated with the JsonConverter attribute:

[JsonConverter(typeof(IgnoringConverter))]
class ClassToIgnore

您还可以将转换器注册为默认转换器，如果您使用ASP.NET Web API，这将非常有用。

You can also register the converter as a default converter which is useful if you're using ASP.NET Web API.

我已经添加了一个控制台应用程序示例来演示其功能：

I have included a Console application sample to demonstrate the functionality:

using System;
using Newtonsoft.Json;

/// <summary>
/// Class we want to serialize.
/// </summary>
class ClassToSerialize
{
    public string MyString { get; set; } = "Hello, serializer!";

    public int MyInt { get; set; } = 9;

    /// <summary>
    /// This will be null after serializing or deserializing.
    /// </summary>
    public ClassToIgnore IgnoredMember { get; set; } = new ClassToIgnore();
}

/// <summary>
/// Ignore instances of this class.
/// </summary>
[JsonConverter(typeof(IgnoringConverter))]
class ClassToIgnore
{
    public string NonSerializedString { get; set; } = "This should not be serialized.";
}

class IgnoringConverter : JsonConverter
{
    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        writer.WriteNull();
    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        return null;
    }

    public override bool CanConvert(Type objectType)
    {
        return objectType == typeof(ClassToIgnore);
    }
}

class Program
{
    static void Main(string[] args)
    {
        var obj = new ClassToSerialize();
        var json = JsonConvert.SerializeObject(obj);

        Console.WriteLine(json);

        obj = JsonConvert.DeserializeObject<ClassToSerialize>(json);

        // note that obj.IgnoredMember == null at this point

        Console.ReadKey();
    }
}

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