比方说你有一个实体,称为Car
这个类包含了需要被验证的财产。
public class Car
{
[Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int Id { get; set; }
// Accepted values have to be between 1 and 5.
public int NeedToBeValidatedRange { get; set; }
}
您必须为我的示例中的所有实体创建一个基类,我将调用实体。
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.ComponentModel.DataAnnotations;
using System.Linq;
/// This is the base class for all entities and it provide a change notfication.
public abstract class Entity : INotifyPropertyChanged
{
// Event fired when the property is changed!
public event PropertyChangedEventHandler PropertyChanged;
/// Called when int property in the inherited class is changed for ther others properties like (double, long, or other entities etc,) You have to do it.
protected void HandlePropertyChange(ref int value, int newValue, string propertyName)
{
if (value != newValue)
{
value = newValue;
this.Validate(propertyName);
this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
/// Validate the property
/// <returns>
/// The list of validation errors
/// </returns>
private ICollection<ValidationResult> PropertyValidator(string propertyName)
{
var validationResults = new Collection<ValidationResult>();
PropertyDescriptor property = TypeDescriptor.GetProperties(this)[propertyName];
Validator.TryValidateProperty(
property.GetValue(this),
new ValidationContext(this, null, null) { MemberName = propertyName },
validationResults);
return validationResults;
}
/// Validates the given property and return all found validation errors.
private void Validate(string propName)
{
var validationResults = this.PropertyValidator(propName);
if (validationResults.Count > 0)
{
var validationExceptions = validationResults.Select(validationResult => new ValidationException(validationResult.ErrorMessage));
var aggregateException = new AggregateException(validationExceptions);
throw aggregateException;
}
}
}
,现在你得modfiy Car类,它应该是这样的:
public class Car : Entity
{
private int id;
private int needToBeValidatedRange;
[Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int Id
{
get
{
return this.id;
}
set
{
this.HandlePropertyChange(ref this.id, value, "Id");
}
}
[Range(1, 5)]
public int NeedToBeValidatedRange
{
get
{
return this.needToBeValidatedRange;
}
set
{
this.HandlePropertyChange(ref this.needToBeValidatedRange, value, "NeedToBeValidatedRange ");
}
}
}
某处在您创建的汽车实体的用户界面:
Car car1 = new Car();
car1.NeedToBeValidatedRange = 3; // This will work!
Car car2 = new Car();
car2.NeedToBeValidatedRange = 6; // This will throw ValidationException
- WPF支持非常好的ValidationException。
- Winforms支持部分ValidationException,但现在您可以自由处理此问题。
的OP已要求EF 5,但希望它适用于EF 4.1的! –
它适用于4.1. –