Question

当我尝试使用带有数据注释的元数据类注册提供程序时，当我使用对象实例而不是类型时，我无法使验证器正常工作。

using System;
using System.ComponentModel.DataAnnotations;
using System.Collections.Generic;
using System.Linq;
using System.ComponentModel;

public class Program
{
    public static void Main()
    {
        /* Should not pass validation */
        var obj = new MyClass()
        {Value = "123456"};

        /* Should pass validation */
        var obj2 = new MyClass()
        {Value = "123456"};

        /* Add custom provider to just the first object */
        var provider = new AssociatedMetadataTypeTypeDescriptionProvider(typeof (MyClass), typeof (MyClassMeta));
        TypeDescriptor.AddProvider(provider, obj);

        Console.WriteLine("obj:");
        Validate(obj);

        Console.WriteLine("obj2:");
        Validate(obj2);
    }

    private static void Validate(object obj)
    {
        ValidationContext context = new ValidationContext(obj, null, null);
        List<ValidationResult> results = new List<ValidationResult>();
        bool valid = Validator.TryValidateObject(obj, context, results, true);
        if (!valid)
        {
            foreach (ValidationResult vr in results)
            {
                Console.Write("Member Name:{0}", vr.MemberNames.First());
                Console.WriteLine(" - {0}", vr.ErrorMessage);
            }
        }
        else
        {
            Console.WriteLine("I am valid.");
        }
    }
}

public class MyClass
{
    [Required]
    public string Value
    {
        get;
        set;
    }
}

public class MyClassMeta
{
    [MaxLength(5)]
    public string Value
    {
        get;
        set;
    }
}

https://dotnetfiddle.net/RlOuTg

我希望将元数据类验证器应用于“ obj”，但是当我运行此代码时它仍然有效。如果我更改代码以使用类型而不是对象，则将验证器应用于该类型的所有实例（按预期方式）。我想在运行时将元数据应用于对象的特定实例。

具有对象实例的TypeDescriptor.AddProvider不应用验证数据注释

0 个答案: