C# 验证嵌套 class 的自定义数据类型（枚举）的属性内的属性

Question

我需要以下帮助。 我有一个基础 class，比如 MyClass，它有一个嵌套的 class，比如 StandardOne。 在 StandardOne 中，我有一些我希望用属性验证的属性。 这些属性适用于常见的数据类型，即字符串、字符等，但我有一些基于简单枚举的属性。 此时，属性的验证不起作用，根据错误提示，因为强制转换。 我尝试了一切，但是，唉，没有成功。

1. 谁能帮我解决错误？
2. 我看到我在验证属性时一次又一次地做同样的代码； 关于如何（也许？）将其转换为扩展的任何建议？ 我不知道.. 欢迎任何建议。

例子：

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;
                    
public class Program
{
    public static void Main()
    {
        Console.WriteLine("Start");
    }

    public class MyClass
    {
        public Standard_One Standard {get;set;}

        private string  _Name;

        public MyClass(string system_name)
        {
            this._Name = system_name;
            this.Standard = new Standard_One();
        }

        public class Standard_One
        {
            private string _MyProperty1;

            [Required(AllowEmptyStrings = false, ErrorMessage = "Field is mandatory.")]
            [StringLength(32, ErrorMessage = "Field value should be between Minimum 1 and Maximum 32 characters.", MinimumLength = 1)]
            [RegularExpression(@"^[a-zA-Z0-9.-]$", ErrorMessage = "Non-valid characters included.")]
            public string MyProperty1
            {
                get
                { return _MyProperty1; }
                set
                {
                    var context = new ValidationContext(value, null, null);
                    var results = new List<ValidationResult>();
                    var attributes = typeof(Standard_One)
                        .GetProperty("MyProperty1")
                        .GetCustomAttributes(true)
                        .OfType<ValidationAttribute>()
                        .ToArray();
                    
                    // All ok
                    if (!Validator.TryValidateValue(value, context, results, attributes))       
                    {
                        foreach (var result in results)
                        {Console.WriteLine("MyProperty1 error: {0}", result.ErrorMessage); }
                    }
                    else
                    {
                        Console.WriteLine("MyProperty1 set to {0}.", value);
                        _MyProperty1 = value;
                    }
                }
            }

            public enum field_sys_type { A, B, G }
            
            [Required(AllowEmptyStrings = false, ErrorMessage = "Field is mandatory.")]
            [StringLength(32, ErrorMessage = "Field value should be between Minimum 1 and Maximum 32 characters.", MinimumLength = 1)]
            [RegularExpression(@"^[a-zA-Z0-9.-]$", ErrorMessage = "Non-valid characters included.")]
            public field_sys_type MyProperty2
            {
                get
                { return _MyProperty2; }
                set
                {
                    var context = new ValidationContext(value, null, null);
                    var results = new List<ValidationResult>();
                    var attributes = typeof(Standard_One)
                        .GetProperty("MyProperty2")
                        .GetCustomAttributes(true)
                        .OfType<ValidationAttribute>()
                        .ToArray();
                    
                    // THROWS System.InvalidCastException: 'Unable to cast object of type 'field_sys_type' to type 'System.String'.'
                    if (!Validator.TryValidateValue(value, context, results, attributes))       
                    {
                        foreach (var result in results)
                        {Console.WriteLine("MyProperty2 error: {0}", result.ErrorMessage); }
                    }
                    else
                    {
                        Console.WriteLine("MyProperty2 set to {0}.", value);
                        _MyProperty2 = value;
                    }
                }
            }
            
        }
    }   // end of MyClass
}

Answer 1

您不应该在属性设置器内部进行验证。 你需要验证你的整个 object 看看例子： https://www.geekinsta.com/manually-validate-with-data-annotations/

 this._Name = system_name;
 this.Standard = new Standard_One();

 var ctx = new ValidationContext(this.Standard);

 // A list to hold the validation result.
 var results = new List < ValidationResult > ();

 if (!Validator.TryValidateObject(this.Standard, ctx, results, true)) {
   foreach(var errors in results) {
     Console.WriteLine("Error {0}", errors);
     return;
   }
 }