将当前日期分配给MVC中的属性 [英] Assign current date to a property in MVC

问题描述

我正在为用户创建一个模型，并且我希望将加入的属性设置为Now().这是我的代码:

I am creating a model for users and I want that property joined was set to Now(). Here's my code:

[DefaultValue(DateTime.Now)]
public DateTime joined {get; set;}

我收到错误消息:

属性参数必须是属性参数类型的常量表达式，typeof表达式或数组创建表达式.

An attribute argument must be a constant expression, typeof expression or array creation expression of an attribute parameter type.

我做错了什么?而做我想要的最好的方法是什么?

What am I doing wrong? And what's the best way to do what I want?

推荐答案

DateTime.Now不是常量，而是在运行时计算的属性，这就是为什么您不能按照建议执行的原因.

DateTime.Now is not a constant, but a property that's computed at runtime, which is why you can't do what you're suggesting.

您可以使用以下任一方法来完成您的建议:

You can do what you're proposing with either:

public class MyClass {
  public DateTime joined { get; set; }
  public MyClass() {
    joined = DateTime.Now;
  }
}

或者:

public class MyClass {
  private DateTime _joined = DateTime.Now;
  public DateTime joined { get { return _joined; } set { _joined = value; } }
}

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