C＃类中的可选属性 [英] Optional property in a C# class

问题描述

Optional property
I want to create a class that has an optional property. I don't want to create a subclass
Example
public class MyClass
    {
        public MyClass( int extraPoperty)
        {
            // Something like this
            if(extraPoperty==1)
            public int ExtraPoperty { get;  set; }

        }

        public int EntityId { get;  set; }
    }

Is this possible?

我尝试过：



我在网上找不到任何东西

What I have tried:

I can not find anything on the web

推荐答案

不 - 你不能在方法或构造函数中定义一个属性，仅在类体内。



你究竟想做什么？为什么你认为你需要这个？

No - you can't define a property within a method or constructor, only within the class body.

What exactly are you trying to do? Why do you think you need this?

最好的赌注可能是一个可以为空的领域

Best bet is probably a nullable field

public int? MyProperty {get;set;}

如果该字段为空，您可以认为它尚未提供。

If the field is null you can assume it hasn't been supplied.

不可能，你的财产是否定义，它不能是有条件的。



但你可以 dynamic 类 ExpandoObject ：

使用Type dynamic（C＃编程指南）| Microsoft Docs [ ^ ]



system.dynamic.expandoobject [ system.dynamic.expandoobject ] < br $> b $ b

创建动态，可扩展的C＃Expando对象 - Rick Strahl的Web日志 [ ^ ]

No it is not possible, your property is either defined or not, it cannot be conditional.

However you can have dynamic classes with ExpandoObject :
Using Type dynamic (C# Programming Guide) | Microsoft Docs[^]

system.dynamic.expandoobject[system.dynamic.expandoobject]

Creating a dynamic, extensible C# Expando Object - Rick Strahl's Web Log[^]

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