如何在类中找到DateTime类型的所有属性？

Question

我需要调整一堆对象的日期时间.

我想循环遍历类的属性,如果类型是dateTime相应调整.

是否有任何形式的"描述类型"我可以使用？

Answer 1

你可以使用反射.

您的方案可能看起来像这样:

    static void Main(string[] args)
    {
        var list = new List<Mammal>();

        list.Add(new Person { Name = "Filip", DOB = DateTime.Now });
        list.Add(new Person { Name = "Peter", DOB = DateTime.Now });
        list.Add(new Person { Name = "Goran", DOB = DateTime.Now });
        list.Add(new Person { Name = "Markus", DOB = DateTime.Now });

        list.Add(new Dog { Name = "Sparky", Breed = "Unknown" });
        list.Add(new Dog { Name = "Little Kid", Breed = "Unknown" });
        list.Add(new Dog { Name = "Zorro", Breed = "Unknown" });

        foreach (var item in list)
            Console.WriteLine(item.Speek());

        list = ReCalculateDOB(list);

        foreach (var item in list)
            Console.WriteLine(item.Speek());
    }

你想在哪里重新计算所有哺乳动物的生日.以上的实现看起来像这样:

internal interface Mammal
{
    string Speek();
}

internal class Person : Mammal
{
    public string Name { get; set; }
    public DateTime DOB { get; set; }

    public string Speek()
    {
        return "My DOB is: " + DOB.ToString() ;
    }
}
internal class Dog : Mammal
{
    public string Name { get; set; }
    public string Breed { get; set; }

    public string Speek()
    {
        return "Woff!";
    }
}

所以基本上你需要做的是使用Relfection,它是一种机制,用于检查类型并获取类型属性以及运行时类似的其他内容.下面是一个关于如何为每个获得DOB的哺乳动物的上述DOB添加10天的示例.

static List<Mammal> ReCalculateDOB(List<Mammal> list)
{
    foreach (var item in list)
    {
        var properties = item.GetType().GetProperties();
        foreach (var property in properties)
        {
            if (property.PropertyType == typeof(DateTime))
                property.SetValue(item, ((DateTime)property.GetValue(item, null)).AddDays(10), null);
        }
    }

    return list;
}

请记住,使用反射可能很慢,而且通常很慢.

但是,上面会打印出这个:

My DOB is: 2010-03-22 09:18:12
My DOB is: 2010-03-22 09:18:12
My DOB is: 2010-03-22 09:18:12
My DOB is: 2010-03-22 09:18:12
Woff!
Woff!
Woff!
My DOB is: 2010-04-01 09:18:12
My DOB is: 2010-04-01 09:18:12
My DOB is: 2010-04-01 09:18:12
My DOB is: 2010-04-01 09:18:12
Woff!
Woff!
Woff!

Answer 2

它被称为反射.

var t = this;
var props = t.GetType().GetProperties();
foreach (var prop in props)
{
    if (prop.PropertyType == typeof(DateTime))
    {
        //do stuff like prop.SetValue(t, DateTime.Now, null);

    }
}