如何使用JsonConverter从System.Text.Json.JsonSerializer.Serialize()中排除要序列化的属性 [英] How to exclude a property from being serialized in System.Text.Json.JsonSerializer.Serialize() using a JsonConverter

问题描述

我希望能够在使用System.Text.Json.JsonSerializer进行序列化时排除属性.我不想在要执行此操作的任何地方都使用JsonIgnore属性.我希望能够通过某种Fluent API定义仅在序列化期间要排除的属性，

I want to be able to exclude a property when serializing using System.Text.Json.JsonSerializer. I don't want to use a JsonIgnore attribute everywhere I want to do this. I would like to be able to define the properties I want to exclude during serialization only, via some kind of Fluent API, which currently does not exist.

我唯一能找到的选择是定义一个JsonConverter并将其添加到我传递给Serialize()方法的JsonSerializerOptions上的Converters列表中，如下所示:

The only option I was able to find is to define a JsonConverter and add it to the list of Converters on the JsonSerializerOptions that I pass to the Serialize() method like so:

var options = new JsonSerializerOptions();
options.Converters.Add(new BookConverter());
json = JsonSerializer.Serialize(book, options);

在JsonConverter中，我必须使用Utf8JsonWriter自己编写整个JSON表示形式，但不包括我不想序列化的属性.仅仅能够排除一个属性，这是很多工作.尽管JsonConverter是.NET团队的一项出色的可扩展性功能，但对于我的用例而言，它只是太底层了.没有人知道其他任何方法来实现属性的排除而不必亲自写出JSON表示吗?

In the JsonConverter I would have to write the entire JSON representation myself using a Utf8JsonWriter, excluding the property I don't want to serialize. This is a lot of work to just be able to exclude a property. While the JsonConverter is a great extensibility feature from the .NET team, its just too low-level for my use case. Does anyone know of any other way to acheive the exclusion of the property without having to write out the JSON representation myself?

我不想执行以下操作:

• 使用属性，或在运行时动态添加属性
• 将属性的访问修饰符更改为private或protected
• 使用3rd party库，因为如果使用Json.NET，我的问题就可以解决.

• Use an attribute, or dynamically add an attribute at runtime
• Change the access modifier of the property to something like private or protected
• Use a 3rd party library, as my issue is solvable if I use Json.NET.

示例:

class Program
{
    void Main()
    {
        // We want to serialize Book but to ignore the Author property
        var book = new Book() { Id = 1, Name = "Calculus", Author = new Author() };

        var json = JsonSerializer.Serialize(book);
        // Default serialization, we get this:
        // json = { "Id": 1, "Name": "Calculus", "Author": {} }

        // Add our custom converter to options and pass it to the Serialize() method
        var options = new JsonSerializerOptions();
        options.Converters.Add(new BookConverter());
        json = JsonSerializer.Serialize(book, options);
        // I want to get this:
        // json = { Id: 1, Name: "Calculus" }
    }
}

public class Author { }

public class Book
{
    public int Id { get; set; }
    public string Name { get; set; }
    public Author Author { get; set; }
}

public class BookConverter : JsonConverter<Book>
{
    public override Book Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
    {
        // Use default implementation when deserializing (reading)
        return JsonSerializer.Deserialize<Book>(ref reader, options);
    }

    public override void Write(Utf8JsonWriter writer, Book value, JsonSerializerOptions options)
    {
        // Serializing. Here we have to write the JSON representation ourselves
        writer.WriteStartObject();

        writer.WriteNumber("Id", value.Id);
        writer.WriteString("Name", value.Name);
        // Don't write Author so we can exclude it

        writer.WriteEndObject();
    }
}

推荐答案

所以我偶然发现了一篇文章，该文章演示了如何在新的System.Text.Json命名空间中使用JsonDocument对象，这是下一个最好的选择流利的API.这是解决这个问题的方法.

So I happened to stumble upon an article that demonstrates how to use the JsonDocument object in the new System.Text.Json namespace and it is the next best thing to a Fluent API. Here is how this question can be solved.

BookConverter.Write()方法:

The BookConverter.Write() method:

public override void Write(Utf8JsonWriter writer, Book value, JsonSerializerOptions options)
{
    writer.WriteStartObject();

    using (JsonDocument document = JsonDocument.Parse(JsonSerializer.Serialize(value)))
    {
        foreach (var property in document.RootElement.EnumerateObject())
        {
            if (property.Name != "Author")
                property.WriteTo(writer);
        }
    }

    writer.WriteEndObject();
}

这篇关于如何使用JsonConverter从System.Text.Json.JsonSerializer.Serialize()中排除要序列化的属性的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！