c# - 使用自定义 ValidationResult 处理数据注释验证

Question

我有一个像这样的自定义 ValidationAttribute :

public class ReceiverRegion : ValidationAttribute
    {
        private RegionService regionService;
        private CityService cityService;

        public ReceiverRegion() : base("Incorrect region code")
        {
            this.regionService = new RegionService();
            this.cityService = new CityService();
        }

        protected override ValidationResult IsValid(object value, ValidationContext validationContext)
        {
            int regionId = Convert.ToInt32(value);
            int plate = Convert.ToInt32((validationContext.ObjectInstance as CorporateOrderItem).ReceiverCity);

            int productGroupId = Convert.ToInt32(validationContext.Items["productGroup"].ToString());

            if (!CheckReceiverRegionExistence(regionId, plate, productGroupId))
            {
                IEnumerable regions = this.regionService.GetList(cityService.GetByPlate(plate).PKCityId);

                return new CorporateOrderValidationResult(base.ErrorMessage, regions.Select(r=>r.Name));
            }
            return <b>CorporateOrderValidationResult.Success</b>;
        }

        private bool CheckReceiverRegionExistence(int plate, int regionId, int productGroup)
        {
            return !(regionService.GetByCityAndRegionIdForProductGroup(plate, regionId, productGroup) == null);
        }
    }

But as you can see in IsValid method, I'm trying to return a custom object which inherits from ValidationResult. My problem is, I can't access the extra members of my CorporateOrderValidationResult instance since IsValid returns the base ValidationResult type. Below is the code where I call validate and get a collection of ValidationResult as return value.

List results = new List();
bool isValid = Validator.TryValidateObject(instance, context, results, true);

我试图将结果对象转换为 List<CorporateOrderValidationResult> ，但无论我尝试什么(例如 --> item as CorporateOrderValidationResult 或 results.OfType<CorporateOrderValidationResult>() 或 (CorporateOrderValidationResult)item) 我要么得到 InvalidCastException 要么 null 值。是否有可能将此结果列表转换为我的自定义结果列表类？谢谢...

Answer 1

我试图重现此行为，但一切都按预期进行:

public class TestClass
{
    [TestValidation]
    public string TestProp { get; set; }
}

public class TestValidationAttribute : ValidationAttribute
{
    protected override ValidationResult IsValid(object value, ValidationContext validationContext)
    {
        return new TestResult();
    }
}

public class TestResult : ValidationResult
{
    public TestResult()
        : base("test")
    {
    }
}

验证代码:

var instance = new TestClass();
var context = new ValidationContext(instance, null, null);
var results = new List<ValidationResult>();
bool isValid = Validator.TryValidateObject(instance, context, results, true);
//Contains one instance of TestResult
var customResults = results.OfType<TestResult>().ToArray();