如何设置在运行时RegularEx pression数据注解的常规前pression说法？ [英] How can I set a RegularExpression data annotation's regular expression argument at runtime?

问题描述

我们管理多个ASP.NET MVC客户端的网站，它们都使用一个数据注解像下面来验证客户电子邮件地址（我没有这里包括正则表达式，为便于阅读）：

We manage several ASP.NET MVC client web sites, which all use a data annotation like the following to validate customer email addresses (I haven't included the regex here, for readability):

[Required(ErrorMessage="Email is required")]
[RegularExpression(@"MYREGEX", ErrorMessage = "Email address is not valid")]
public string Email { get; set; }

我想要做的是集中该正前pression，因此，如果我们做出改变它，所有的网站立即把它捡起来，我们不必手动更改每之一。

What I would like to do is to centralise this regular expression, so that if we make a change to it, all of the sites immediately pick it up and we don't have to manually change it in each one.

问题是数据注解的正则表达式参数必须是恒定的，所以我不能分配（这是我的第一个想法），我从在运行配置文件或数据库中检索的值。

The problem is that the regex argument of the data annotation must be a constant, so I cannot assign a value I've retrieved from a config file or database at runtime (which was my first thought).

谁能帮我一个聪明的解决这个，如果不行的话，另一种方法，将努力实现同样的目标？还是这恰恰需要我们写一个专门定制验证属性，它会接受非恒定值？

Can anyone help me with a clever solution to this—or failing that, an alternative approach which will work to achieve the same goal? Or does this just require us to write a specialist custom validation attribute which will accept non-constant values?

推荐答案

最简单的方法是写一个自定义的 ValidationAttribute 从 RegularEx $继承p $ pssionAttribute ，所以是这样的：

The easiest way is to write a custom ValidationAttribute that inherits from RegularExpressionAttribute, so something like:

public class EmailAttribute : RegularExpressionAttribute
    {
        public EmailAttribute()
            : base(GetRegex())
        { }

        private static string GetRegex()
        {
            // TODO: Go off and get your RegEx here
            return @"^[\w-]+(\.[\w-]+)*@([a-z0-9-]+(\.[a-z0-9-]+)*?\.[a-z]{2,6}|(\d{1,3}\.){3}\d{1,3})(:\d{4})?$";
        }
    }

这样的话，你仍然保持使用内置的正则表达式验证，但你可以自定义。你只是简单地使用它，如：

That way, you still maintain use of the built in Regex validation but you can customise it. You'd just simply use it like:

[Email(ErrorMessage = "Please use a valid email address")]

最后，要获得客户端验证工作，你只会增加你的Ap​​plication_Start方法下面在Global.asax内，告诉MVC使用普通的常规前pression验证这个验证：

Lastly, to get to client side validation to work, you would simply add the following in your Application_Start method within the global.asax, to tell MVC to use the normal regular expression validation for this validator:

DataAnnotationsModelValidatorProvider.RegisterAdapter(typeof(EmailAttribute), typeof(RegularExpressionAttributeAdapter));

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