ASP.NET MVC 3数据注释：动态添加验证

I'm new with data annotation. I'd like to know if it possible (and how) to add some validation dynamically. It is very extensive to explain why, but I've a ViewModel that receives and object when created. In that object I must check for some property and depending its value I should have or not some validations.

我是数据注释的新手。我想知道是否有可能（以及如何）动态添加一些验证。解释原因非常广泛，但我创建的ViewModel接收和对象。在那个对象中，我必须检查一些属性，并根据其值，我应该有或没有一些验证。

An example:

一个例子：

public class ProfileViewModel
{
    [Required(ErrorMessage = "The field {0} is required")]
    [Display(Name = "Client Code")]
    public int ClientCode { get; set; }

    [Required(ErrorMessage = "The field {0} is required")]
    [StringLength(100, ErrorMessage = "The field {0} must have up to 100 characters.")]
    [Display(Name = "Company")]
    public string Company { get; set; }

    [StringLength(50, ErrorMessage = "The field {0} must have up to 50 characters.")]
    [Display(Name = "Name")]
    public string Name { get; set; }

    [StringLength(50, ErrorMessage = "The field {0} must have up to 50 characters.")]
    [Display(Name = "LastName")]
    public string LastName { get; set; }

    public ProfileViewModel(User usr)
    {
        if (usuario.ClientCode != null)
        {
            ClientCode = Convert.ToInt32(usr.ClientCode);
        }
        else
        {
             //ClientCode and Company are not yet required.
             //Name and LastName are now required.
        }
        Company = usr.Company;
        Name = usr.Name;
        LastName = usr.LastName;
    }
}

3 个解决方案

#1

I think that the simplest way of doing what I wanted is implementing IValidatableObject:

我认为实现我想要的最简单的方法是实现IValidatableObject：

public class Product : IValidatableObject
{
    public int Prop1 { get; set; }
    public int Prop2 { get; set; }

    public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
    {
        if (Prop1 < Prop2)
            yield return new ValidationResult("Property 1 can't be less than Property 2");
    }
}

另请参见：使用ASP.NET MVC 3进行类级别模型验证

#2

Custom Attribute:

自定义属性：

[AttributeUsage(AttributeTargets.Property, AllowMultiple = true, Inherited = true)]
public class CustomRequiredIfAttribute : CustomAttribute
{
    private RequiredAttribute innerAttribute = new RequiredAttribute();
    public string DependentProperty { get; set; }
    public object TargetValue { get; set; }

    public CustomRequiredIfAttribute()
    {
    }

    public CustomRequiredIfAttribute(string dependentProperty, object targetValue)
        : base()
    {
        this.DependentProperty = dependentProperty;
        this.TargetValue = targetValue;
    }

    public override bool IsValid(object value)
    {
        return innerAttribute.IsValid(value);
    }
}

Custom RequiredIfValidator

自定义RequiredIfValidator

using System;
using System.Collections.Generic;
using System.Web.Mvc;

namespace Custom.Web.Validation
{
    public class RequiredIfValidator : DataAnnotationsModelValidator<CustomRequiredIfAttribute>
    {
        public RequiredIfValidator(ModelMetadata metadata, ControllerContext context, CustomRequiredIfAttribute attribute)
            : base(metadata, context, attribute)
        {
        }

        public override IEnumerable<ModelClientValidationRule> GetClientValidationRules()
        {
            return base.GetClientValidationRules();
        }

        public override IEnumerable<ModelValidationResult> Validate(object container)
        {
            // get a reference to the property this validation depends upon
            var field = Metadata.ContainerType.GetProperty(Attribute.DependentProperty);

            if (field != null)
            {
                // get the value of the dependent property
                object value = field.GetValue(container, null);

                // compare the value against the target value
                if (this.IsEqual(value) || (value == null && Attribute.TargetValue == null))
                {
                    // match => means we should try validating this field
                    if (!Attribute.IsValid(Metadata.Model))
                    {
                        // validation failed - return an error
                        yield return new ModelValidationResult { Message = ErrorMessage };
                    }
                }
            }
        }

        private bool IsEqual(object dependentPropertyValue)
        {
            bool isEqual = false;

            if (Attribute.TargetValue != null && Attribute.TargetValue.GetType().IsArray)
            {
                foreach (object o in (Array)Attribute.TargetValue)
                {
                    isEqual = o.Equals(dependentPropertyValue);
                    if (isEqual)
                    {
                        break;
                    }
                }
            }
            else
            {
                isEqual = Attribute.TargetValue.Equals(dependentPropertyValue);
            }

            return isEqual;
        }
    }
}

注册自定义DataAnnotationsModelValidatorProvider

DataAnnotationsModelValidatorProvider.RegisterAdapter(typeof(CustomRequiredIfAttribute), typeof(RequiredIfValidator));

Use this CustomRequiredIf in the ViewModel

在ViewModel中使用此CustomRequiredIf

[CustomRequiredIf("CategoryId", 3, ErrorMessageResourceName = GlobalResourceLiterals.AccountGroup_Required)]
public string AccountGroup { get; set; }

#3

Heres the updated MVC 3 version of that blog post http://blogs.msdn.com/b/simonince/archive/2011/02/04/conditional-validation-in-asp-net-mvc-3.aspx

下面是该博客文章的更新MVC 3版本http://blogs.msdn.com/b/simonince/archive/2011/02/04/conditional-validation-in-asp-net-mvc-3.aspx

#1