自定义属性以更改属性值 [英] Custom attribute to change property value

问题描述

我有一个叫say的类

Class1
  public string store { get; set; }

我要用这样的东西装饰它；

What I want is to decorate it with something like this;

Class1
  [GetStoreNumberFromName]
  [IsNumeric]
  public string store {get; set; }

因此，值可能是 1234 ，或者可能是 1234-商店名称

So the value might be 1234, or it might be 1234 - Store name

我需要做的是检查传递的值是否具有里面只有数字。如果不是这样，那么在第二个示例中，我需要获取前4个chrs并将属性的值更改为该值。

What I need to do is check to see if the value passed has only numbers in it. If it doesn't then I need, in the second example, to grab the first 4 chrs and change the value of the property to that.

因此，如果传入值是 1234-商店名称，然后在 [GetStoreNumberFromName] 的末尾， store的值应该为 1234 ，以便 [IsNumeric] 将作为有效值通过。

So if the passed in value was 1234 - Store Name then at the end of [GetStoreNumberFromName] the value of store should be 1234 so that [IsNumeric] will pass as valid.

推荐答案

好吧..希望我已经理解您的要求：

Okay.. hopefully I've understood your requirement:

class GetStoreNumberFromNameAttribute : Attribute {
}

class Class1 {
    [GetStoreNumberFromName]
    public string store { get; set; }
}

class Validator<T>
{
    public bool IsValid(T obj)
    {
        var propertiesWithAttribute = typeof(T)
                                      .GetProperties()
                                      .Where(x => Attribute.IsDefined(x, typeof(GetStoreNumberFromNameAttribute)));

        foreach (var property in propertiesWithAttribute)
        {
            if (!Regex.Match(property.GetValue(obj).ToString(), @"^\d+$").Success)
            {
                property.SetValue(obj, Regex.Match(property.GetValue(obj).ToString(), @"\d+").Groups[0].Value);
            }
        }

        return true;
    }
}

..用法：

var obj = new Class1() { store = "1234 - Test" };
Validator<Class1> validator = new Validator<Class1>();
validator.IsValid(obj);

Console.WriteLine(obj.store); // prints "1234"

..显然需要在您的端进行一些更改..但是它应该给你有一个主意（我知道方法的命名可能不是最好的..：/）

..obviously needs some changes on your end.. but it should give you an idea (I'm aware that the method naming probably isn't the best.. :/)

如果我完全忘记了要点，请告诉我，我会删除。

If I've missed the point entirely let me know and I'll delete.

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