F#:如何将Json.NET [JsonConstructor]属性应用于主要构造函数? [英] F#: How to apply Json.NET [JsonConstructor] attribute to primary constructor?

问题描述

我正在尝试在F#中执行某些操作，例如JsonConstructorAttribute示例> Json.NET文档:

I'm trying to do something in F# like the JsonConstructorAttribute example in the Json.NET documentation:

public class User
{
    public string UserName { get; private set; }
    public bool Enabled { get; private set; }

    public User()
    {
    }

    [JsonConstructor]
    public User(string userName, bool enabled)
    {
        UserName = userName;
        Enabled = enabled;
    }
}

F#中的类似物似乎类似于以下内容，但在[<JsonConstructor>]的放置位置时出现错误:

The analog in F# appears to be something like the following, but I'm getting an error on the placement of [<JsonConstructor>]:

[<JsonConstructor>] // ERROR! (see below)
type User (userName : string, enabled : bool) =
    member this.UserName = userName
    member this.Enabled = enabled

错误是

此属性不适用于此语言元素

This attribute is not valid for use on this language element

那么，如何用[<JsonConstructor>]装饰主构造函数?

So then, how do I decorate the primary constructor with [<JsonConstructor>]?

推荐答案

事实证明，这很简单.通过将[<JsonConstructor>]放在主要构造函数的参数列表之前来定位主要构造函数:

It turns out that it's pretty easy. Target the primary constructor by placing [<JsonConstructor>] just before the primary constructor's parameter list:

type User [<JsonConstructor>] (userName : string, enabled : bool) =
    member this.UserName = userName
    member this.Enabled = enabled

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