获取数据注解从模型属性 [英] Get Data Annotations attributes from model

问题描述

我要创建自定义的客户端验证，但我想定义的验证规则通过数据注释在业务逻辑层属性。我怎样才能访问运行时模型验证属性？

I want to create custom client-side validator, but I want define validation rules via Data Annotations attributes at business logic layer. How can I access model validation attributes in runtime?

我想写'发电机'，它会转换成该code：

I want to write 'generator', which will convert this code:

public class LoginModel
{
    [Required]
    [MinLength(3)]
    public string UserName { get; set; }

    [Required]
    public string Password { get; set; }
}

到这一个：

var loginViewModel= {
    UserName: ko.observable().extend({ minLength: 3, required: true }),
    Password: ko.observable().extend({ required: true })
};

但不从的.cs源，当然。 =）

But not from .cs sources, of course. =)

也许反射？

UPD

我发现这个方法：<一href=\"http://msdn.microsoft.com/en-us/library/system.web.mvc.htmlhelper.getunobtrusivevalidationattributes%28v=vs.108%29.aspx\"相对=nofollow> MSDN 。但不知道如何使用它。

I've found this method: MSDN. But can't understand how to use it.

推荐答案

这是在通用办法如何做到这一点：

This is the universal way how to do this:

private string GenerateValidationModel<T>()
{
    var name = typeof(T).Name.Replace("Model", "ViewModel");
    name = Char.ToLowerInvariant(name[0]) + name.Substring(1);

    var validationModel = "var " + name + " = {\n";

    foreach (var prop in typeof(T).GetProperties())
    {
        object[] attrs = prop.GetCustomAttributes(true);
        if (attrs == null || attrs.Length == 0)
            continue;

        string conds = "";

        foreach (Attribute attr in attrs)
        {
            if (attr is MinLengthAttribute)
            {
                conds += ", minLength: " + (attr as MinLengthAttribute).Length;
            }
            else if (attr is RequiredAttribute)
            {
                conds += ", required: true";
            }
            // ...
        }

        if (conds.Length > 0)
            validationModel += String.Format("\t{0}: ko.observable().extend({{ {1} }}),\n", prop.Name, conds.Trim(',', ' '));
    }

    return validationModel + "};";
}

用法：

string validationModel = GenerateValidationModel<LoginModel>();

输出：

var loginViewModel = {
    UserName: ko.observable().extend({ minLength: 3, required: true}),
    Password: ko.observable().extend({ required: true}),
};

这是好主意，缓存输出

It's good idea to cache the output

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