用于验证结束日期的自定义注释不会早于开始日期

Question

对于我的预订系统，我需要检查用户在表单中输入的结束日期是否早于用户在表单中输入的开始日期。我正在使用 ASP.NET MVC 4 C Sharp。

我可以使用自定义注释来做到这一点吗？到目前为止我有这个，但是模型类中的日期下方出现红线，上面写着“属性参数必须是常量表达式......”

    private readonly DateTime _startDate;
    private readonly DateTime _endDate;

    public DateComparisonAttribute(DateTime startDate, DateTime endDate) : base ("{1} is greater than {0}. The end date must come before start date")
    {
        _startDate = startDate;
        _endDate = endDate;
    }

    protected override ValidationResult IsValid(object value, ValidationContext validationContext)
    {
        if (value != null)
        {
            if (_endDate < _startDate)
            {
                var errorMessage = FormatErrorMessage(validationContext.DisplayName);
                return new ValidationResult("End Date Must Come After Start Date");
            }
        }
        return ValidationResult.Success;
    }

型号：

    [DateComparison(StartDate, EndDate, ErrorMessage = "Dates")]
    [DisplayName("Start Date (MM/DD/YYYY)")]
    public DateTime StartDate { get; set; }
    [DisplayName("End Date (MM/DD/YYYY)")]
    public DateTime EndDate { get; set; }

Answer 1

这是我之前根据Brad wilsons blog 的信息编写的一篇

C# 属性

public sealed class IsDateAfterAttribute: ValidationAttribute, IClientValidatable
  {
    protected abstract string GetValidationType();
    protected abstract bool CompareValues(DateTime value, DateTime propertyTestedValue, out ValidationResult validationResult);

    protected readonly string testedPropertyName;
    protected readonly bool allowEqualDates;

    protected int _maxSearchableDaysAhead;

    public IsDateAfterAttribute(string testedPropertyName, bool allowEqualDates = false)
    {
      this.testedPropertyName = testedPropertyName;
      this.allowEqualDates = allowEqualDates;
    }

    protected override ValidationResult IsValid(object value, ValidationContext validationContext)
    {
      var propertyTestedInfo = validationContext.ObjectType.GetProperty(this.testedPropertyName);
      if (propertyTestedInfo == null)
      {
        return new ValidationResult(string.Format("unknown property {0}", this.testedPropertyName));
      }

      var propertyTestedValue = propertyTestedInfo.GetValue(validationContext.ObjectInstance, null);

      if (value == null || !(value is DateTime))
      {
        return ValidationResult.Success;
      }

      if (propertyTestedValue == null || !(propertyTestedValue is DateTime))
      {
        return ValidationResult.Success;
      }

      ValidationResult returnVal;
      if (CompareValues((DateTime)value, (DateTime)propertyTestedValue, out returnVal))
      {
        return returnVal;
      }
      else
      {
        return new ValidationResult(FormatErrorMessage(validationContext.DisplayName));
      }



    }

    protected override bool CompareValues(DateTime value, DateTime propertyTestedValue, out ValidationResult validationResult)
{
  validationResult = null;
  // Compare values
  if (value <= propertyTestedValue)
  {
    if (this.allowEqualDates)
    {
      validationResult = ValidationResult.Success;
      return true;
    }
    if (value < propertyTestedValue)
    {
      validationResult = ValidationResult.Success;
      return true;
    }

  }


  return false;
}

    public IEnumerable<ModelClientValidationRule> GetClientValidationRules(ModelMetadata metadata, ControllerContext context)
    {

      this._maxSearchableDaysAhead = Setting.GetSettingValue(SettingNames.MaxSearchableDaysAhead, 548);

      var rule = new ModelClientValidationRule
      {
        ErrorMessage = string.Format(this.ErrorMessageString, _maxSearchableDaysAhead),
        ValidationType = "isdateafter"
      };
      rule.ValidationParameters["propertytested"] = this.testedPropertyName;
      rule.ValidationParameters["allowequaldates"] = this.allowEqualDates;
      yield return rule;
    }
  }

JS

$.validator.unobtrusive.adapters.add(
    'isdateafter', ['propertytested', 'allowequaldates'], function (options) {
        options.rules['isdateafter'] = options.params;
        options.messages['isdateafter'] = options.message;
    });
    $.validator.addMethod("isdateafter", function (value, element, params) {
        var parts = element.name.split(".");
        var prefix = "";
        if (parts.length > 1)
            prefix = parts[0] + ".";
        var startdatevalue = $('input[name="' + prefix + params.propertytested + '"]').val();
        if (!value || !startdatevalue)
            return true;
        if (params.allowequaldates && params.allowequaldates.toLowerCase() == "true") 
                {
                    return Date.parse(startdatevalue) <= Date.parse(value); 
                }
                else
                {
                    return Date.parse(startdatevalue) < Date.parse(value);
                }
    });

添加到模型

[DisplayName("Departure Dates")]
 public DateTime? DepartureFrom { get; set; }

 [DisplayName("Departure Dates")]
 [IsDateAfter("DepartureFrom", true, ErrorMessage = "* Departure To Date must be after Departure From Date")]
 public DateTime? DepartureTo { get; set; }

Answer 2

属性必须是常量，因为它们是在编译时添加到程序集的。所以，不，你不能通过自定义注释得到你想要的。