自定义验证属性永远不会被验证

Question

我正在尝试创建一个自定义验证属性，只需要一个字段，具体取决于另一个字段的结果。

我遇到的问题是 IsValid 块永远不会被调用。数据似乎正在进入字段，我已经能够通过断点进行检查。

我尝试在OnPostAsync 中放置一个TryValidateModel(this)，这可以通过断点，但我可以看到发生了另一个错误。

请求的操作对 DynamicMethod 无效

下面是我的代码。任何帮助将不胜感激。

        public class PageOneModel : PageModel
        {
            [BindProperty]
            public bool CompanyHouseToggle { get; set; }

            [BindProperty]
            [StringLength(60, MinimumLength = 3)]
            [RequiredIf("CompanyHouseToggle", desiredvalue: "true")]
            public string CompanyNumber { get; set; }

            [BindProperty]
            [StringLength(60, MinimumLength = 3)]
            public string OrganisationName { get; set; }

            [BindProperty]
            [RegularExpression(pattern: "(GB)?([0-9]{9}([0-9]{3})?|[A-Z]{2}[0-9]{3})", ErrorMessage = "This VAT number is not recognised")]
            public string VatNumber { get; set; }

            public void OnGet()
            {
            }

            public async Task<IActionResult> OnPostAsync()
            {
                if (!ModelState.IsValid)
                {
                    return Page();
                }

                RedirectToPage("2");
            }
        }

        public class RequiredIfAttribute : System.ComponentModel.DataAnnotations.ValidationAttribute
        {
            private String PropertyName { get; set; }
            private Object DesiredValue { get; set; }

            public RequiredIfAttribute(String propertyName, Object desiredvalue)
            {
                this.PropertyName = propertyName;
                this.DesiredValue = desiredvalue;
            }

            protected override ValidationResult IsValid(object value, ValidationContext context)
            {
                var property = context.ObjectType.GetProperty(PropertyName);

                if (property == null)
                    throw new ArgumentException("Property with this name not found");

                // Just for testing purposes.
                return new ValidationResult(ErrorMessage);

            }
        }

Answer 1

我建议你从 ReuiredAttribute 继承。它完全适合我。

public class RequiredUnlessDeletingAttribute : RequiredAttribute
{
    string DeletingProperty;

    /// <summary>
    /// Check if the object is going to be deleted skip the validation.
    /// </summary>
    /// <param name="deletingProperty">The boolean property`s name which shows the object will be deleted.</param>
    public RequiredUnlessDeletingAttribute(string deletingProperty = "MustBeDeleted") =>
        DeletingProperty = deletingProperty;

    protected override ValidationResult IsValid(object value, ValidationContext validationContext)
    {
        var property = validationContext.ObjectType.GetProperty(deletingProperty);

        if ((bool)property.GetValue(validationContext.ObjectInstance))
            return ValidationResult.Success;

        return base.IsValid(value, validationContext);

    }
}

查看完整实现here