C#继承类失去“引用”

Question

我有一个部分类，使用了接口，因为由于另一个部分类已经从Entity Framework 4自动生成并继承了ObjectContext，所以我无法继承原始的抽象类。

下面是我的部分类：

namespace Model
{
    using Microsoft.Practices.EnterpriseLibrary.Validation;
    using Microsoft.Practices.EnterpriseLibrary.Validation.Validators;
    using Utilities.BusinessRules;
    using Utilities.BusinessRules.Rules;

    [HasSelfValidation]
    public partial class MyObject : IBusinessObject
    {
        private readonly IBusinessObject businessObject = new BusinessObject();

        private IBusinessObject BusinessObject
        {
            get
            {
                return businessObject;
            }
        }

        public Comment()
        {
            AddRule(new ValidateRequired("Title"));
        }

        public void AddRule(BusinessRule rule)
        {
            BusinessObject.AddRule(rule);
        }

        [SelfValidation]
        public void Validate(ValidationResults results)
        {
            BusinessObject.Validate(results);
        }
    }
}

这里是界面：

namespace Utilities.BusinessRules
{
    using Microsoft.Practices.EnterpriseLibrary.Validation;

    public interface IBusinessObject
    {
        void AddRule(BusinessRule rule);

        void Validate(ValidationResults results);
    }
}

实现方式如下：

namespace Utilities.BusinessRules
{
    using System.Collections.Generic;
    using System.Linq;
    using Microsoft.Practices.EnterpriseLibrary.Validation;
    using Microsoft.Practices.EnterpriseLibrary.Validation.Validators;

    public class BusinessObject : IBusinessObject
    {
        private readonly IList<BusinessRule> businessRules = new List<BusinessRule>();

        public void AddRule(BusinessRule rule)
        {
            this.businessRules.Add(rule);
        }

        [SelfValidation]
        public void Validate(ValidationResults results)
        {
            foreach (var rule in this.businessRules)
            {
                if (!rule.Validate(this))
                {
                     results.AddResult(new ValidationResult(rule.ErrorMessage, this, rule.Key, rule.Tag, null));
                }
            }
        }
    }
}

不要担心规则，它们是有效的。问题在于如果我在测试项目中使用抽象类，则BusinessObject中的Validate()方法将正确地将(this)标识为继承抽象类的任何类（在本例中，我希望这是MyObject）。 不幸的是，切换到接口后，(this)失去了继承类，并且将其标识为BusinessObject。 如何使继承类得到正确的标识？ 下面是调用控制台类：

namespace ModelConsumer
{
    using Model;
    using System;
    using Microsoft.Practices.EnterpriseLibrary.Validation;

    class Program
    {
        static void Main(string[] args)
        {
            using (var myEntities = new MyEntities())
            {
                var myObject= new MyObject();

                myObject.Title = "Credo";

                var validationResults = Validation.Validate(myObject);

                if (validationResults.IsValid)
                {
                    myEntities.MyObjects.AddObject(myObject);
                    //myEntities.SaveChanges();

                    Console.WriteLine("Valid.");
                }
                else
                {
                    foreach (var validationResult in validationResults)
                    {
                        Console.WriteLine(validationResult.Message);
                    }
                }

                Console.Read();
            }
        }
    }
}

这段代码应该是有效的，但实际上会被认定为无效，因为(this)被识别为BusinessObject类型而不是MyObject类型。

啊！我离成功如此之近，真是令人沮丧。

Richard

- Richard

---

为什么 public Comment() 没有返回类型？ - leppie

那是一个构造函数，所以没有返回类型。 - Richard

Answer 1

我认为你的BusinessObject实现是基于继承的。但是，现在你将其用作组合对象，需要进行一些更改：

public interface IBusinessObjectValidator
{
  void AddRule(BusinessRule rule);

  void Validate(IBusinessObject target, ValidationResults results);
}


Public class BusinessObject: IBusinessObjectValidator
{
...

  public void Validate(IBusinssObject target, ValidationResults results)
  {
      foreach (var rule in this.businessRules)
      {
          if (!rule.Validate(target))
          {
             results.AddResult(new ValidationResult(rule.ErrorMessage, target, rule.Key, rule.Tag, null));
          }
      }
  }
}

然后您将按以下方式使用它:

[HasSelfValidation]
    public partial class MyObject : IBusinessObject
    {
        private readonly IBusinessObjectValidator validator = new BusinessObject();

        private IBusinessObjectValidator BusinessObjectValidator
        {
            get
            {
                return validator ;
            }
        }
    public Comment()
    {
        AddRule(new ValidateRequired("Title"));
    }

    public void AddRule(BusinessRule rule)
    {
        validator .AddRule(rule);
    }

    [SelfValidation]
    public void Validate(ValidationResults results)
    {
        validator.Validate(this, results);
    }
}

基本上，我们正在说我们将在外部实现验证器，因此需要将目标对象（正在进行验证的对象）传递给验证方法。我还建议将BusinessObject重命名为BusinessObjectValidtor。

- VinayC

---

嗨，感谢您的回复。我认为那绝对是正确的方向。但是如果将BusinessObject重命名为BusinessObjectValidator（好主意），那么您代码中所引用的IBusinessObject / BusinessObject是什么？ - Richard

明白了！这是第二个界面。稍微调整一下，现在它可以工作了 :) 非常感谢。 - Richard