使用 System.Text.Json 反序列化匿名类型 [英] Deserialize anonymous type with System.Text.Json

问题描述

我正在为 .NET Core 3.x 更新一些应用程序，作为其中的一部分，我试图从 Json.NET 转移到新的 System.Text.Json 类.使用 Json.NET，我可以像这样反序列化匿名类型:

I am updating some apps for .NET Core 3.x, and as part of that I'm trying to move from Json.NET to the new System.Text.Json classes. With Json.NET, I could deserialize an anonymous type like so:

var token = JsonConvert.DeserializeAnonymousType(jsonStr, new { token = "" }).token;

新命名空间中是否有等效的方法?

Is there an equivalent method in the new namespace?

推荐答案

从 .Net 5.0 开始，System.Text.Json.从 如何在 System.Text.Json 中使用不可变类型和非公共访问器:

As of .Net 5.0, deserialization of immutable types -- and thus anonymous types -- is supported by System.Text.Json. From How to use immutable types and non-public accessors with System.Text.Json:

System.Text.Json 可以使用参数化构造函数，这使得反序列化不可变类或结构成为可能.对于一个类，如果唯一的构造函数是参数化的，则将使用该构造函数.

System.Text.Json can use a parameterized constructor, which makes it possible to deserialize an immutable class or struct. For a class, if the only constructor is a parameterized one, that constructor will be used.

由于匿名类型只有一个构造函数，它们现在可以成功反序列化.为此，定义一个辅助方法，如下所示:

As anonymous types have exactly one constructor, they can now be deserialized successfully. To do so, define a helper method like so:

public static partial class JsonSerializerExtensions
{
    public static T DeserializeAnonymousType<T>(string json, T anonymousTypeObject, JsonSerializerOptions options = default)
        => JsonSerializer.Deserialize<T>(json, options);

    public static ValueTask<TValue> DeserializeAnonymousTypeAsync<TValue>(Stream stream, TValue anonymousTypeObject, JsonSerializerOptions options = default, CancellationToken cancellationToken = default)
        => JsonSerializer.DeserializeAsync<TValue>(stream, options, cancellationToken); // Method to deserialize from a stream added for completeness
}

现在你可以:

var token = JsonSerializerExtensions.DeserializeAnonymousType(jsonStr, new { token = "" }).token;

演示小提琴 此处.

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