我在MVC4中使用实体框架,我有以下域类。
我的问题是这样,我如何将SalePrice的值限制为< = Price?我一直在寻找一个合适的属性,可以做到这一点,但没有找到一个。
编辑:
假设一个人在准备提交表格时输入20.00美元的价格,然后他们输入25.00美元的促销价。该计划将禁止此项,因为销售价格不能高于该项目的价格。我想知道是否有[Attribute]
可以对SalePrice强制执行此限制。
public class MedicalProduct
{
[Key]
public int ID { get; set; }
[Required]
[StringLength(50)]
public string Name { get; set; }
[Required]
[DataType(DataType.Currency)]
public double Price { get; set; }
// needs to be less than price.
[Required]
[DataType(DataType.Currency)]
public double SalePrice { get; set; }
// is a foreign key
public int BrandID { get; set; }
}
答案 0 :(得分:2)
我会创建一个自定义ValidationAttribute
来完全按照您的要求执行操作。该属性需要与之比较的propety名称和ComparisonType
。我在下面创建了一个非常快速的示例:
public enum ComparisonType
{
LessThan,
LessThanOrEqual,
Equal,
GreaterThanOrEqual,
GreaterThan,
NotEqual
}
public sealed class ComparisonAttribute : ValidationAttribute
{
string PropertyToCompare { get; set; }
ComparisonType Type { get; set; }
public ComparisonAttribute(string propertyToCompare, ComparisonType type)
{
PropertyToCompare = propertyToCompare;
Type = type;
}
protected override ValidationResult IsValid(object value, ValidationContext validationContext)
{
if (validationContext.ObjectInstance == null || value == null)
return new ValidationResult("Cannot compare null values");
PropertyInfo property = validationContext.ObjectType.GetProperty(PropertyToCompare);
object propertyValue = property.GetValue(validationContext.ObjectInstance, null);
string errorMessage = "";
if (value is IComparable)
{
int compVal = ((IComparable)value).CompareTo(propertyValue);
switch (Type)
{
case ComparisonType.LessThan:
errorMessage = compVal < 0 ? "" : string.Format("{0} is not less than {1}", validationContext.DisplayName, property.Name);
break;
case ComparisonType.LessThanOrEqual:
errorMessage = compVal <= 0 ? "" : string.Format("{0} is not less than or equal to {1}", validationContext.DisplayName, property.Name);
break;
case ComparisonType.Equal:
errorMessage = compVal == 0 ? "" : string.Format("{0} is not equal to {1}", validationContext.DisplayName, property.Name);
break;
case ComparisonType.GreaterThanOrEqual:
errorMessage = compVal >= 0 ? "" : string.Format("{0} is not greater than or equal to {1}", validationContext.DisplayName, property.Name);
break;
case ComparisonType.GreaterThan:
errorMessage = compVal > 0 ? "" : string.Format("{0} is not greater than {1}", validationContext.DisplayName, property.Name);
break;
case ComparisonType.NotEqual:
errorMessage = compVal != 0 ? "" : string.Format("{0} cannot be equal to {1}", validationContext.DisplayName, property.Name);
break;
default:
errorMessage = "";
break;
}
}
if (String.IsNullOrEmpty(errorMessage))
return ValidationResult.Success;
return new ValidationResult(errorMessage);
}
}
public class Model
{
[Comparison("Value2", ComparisonType.LessThanOrEqual)]
public int Value1 { get; set; }
public int Value2 { get; set; }
}
答案 1 :(得分:1)
您可以考虑使public double SalePrice { get; set; }
成为具有支持字段的功能更全面的属性。然后,在允许Price
成为SalePrice
之前,您需要测试set
的值。这是一个简单的例子:
private double _salePrice;
public double SalePrice
{
get { return _salePrice; }
set
{
// only set _salePrice if it's less than
// or equal to Price
if(value <= Price)
_salePrice = value;
}
}
试一试......
[编辑] - 我看到你稍微改了一下这个问题,所以要添加一个,CompareAttribute
可以用来相互验证两个属性(不过,我某些这仅限于字符串值 - 将确认)。另外,请看一下这个页面,它有一个看起来很好,很灵活的自定义解决方案,可能适合您:http://forums.asp.net/t/1924941.aspx。 gorra head - 00:43在英国!!