使实体类关闭以进行更改 [英] Making Entity Class Closed for Changes

问题描述

我有一个数据库关系如下所示。域对象是基于LINQ to SQL ORM创建的。

付款包括现金付款和礼品券付款。假设购买总额为550.可以支付以下组件

  1礼品券价值300 
 
 1礼品券价值200 
 
我现金货币价值50 
  

我正在插入新的付款使用ORM的InsertOnSubmit功能记录。以下代码正常工作。但是，如果我公司正在使用信用卡引入新的付款组件，我需要更改我的付款域类。仍然使用 ORM ，

如何使支付类别开启扩展和关闭更改注意：付款类有行为（例如GetTotalAmountCollected）。我正在努力使付款类满足OCP。

注意：优惠券类型有一个特定的行为。优惠券发行日期小于1/1/2000，不应用于总金额的计算（即CouponValue应为零）。请参阅使用策略模式重建代码。

注意：我正在使用 .Net 4.0

参考：

1. 获取错误当使用ObjectContext.AddObject与实体框架


2. 使用策略模式重构代码


3. 喜欢组合继承？


4. 代码优先与模型/数据库优先




6. C＃由代表vs OOP的策略设计模式


7. 如何使用C＃中的策略模式


8. 继承EF代码首先：第2部分 - 每种类型表（TPT）
   http://weblogs.asp.net/manavi/archive/2010 /12/28/inheritance-mapping-strategies-with-entity-framework-code-first-ctp5-part-2-table-per-type-tpt.aspx




C＃代码：

  public class PaymentAppService 
 {
 public RepositoryLayer.ILijosPaymentReposi tory存储库{get;组; } 
 
 public void MakePayment（）
 {
 DBML_Project.Payment paymentEntity = new DBML_Project.Payment（）; 
 paymentEntity.PaymentID = 1; 
 paymentEntity.PaymentType =PurchaseP; 
 
 DBML_Project.CashPayment cashObj = new DBML_Project.CashPayment（）; 
 cashObj.CashPaymentID = 1; 
 cashObj.CurrencyNumber = 123; 
 cashObj.CurrencyValue = 100; 
 
 DBML_Project.GiftCouponPayment giftCouponObj = new DBML_Project.GiftCouponPayment（）; 
 giftCouponObj.GiftCouponPaymentID = 1; 
 giftCouponObj.CouponValue = 200; 
 giftCouponObj.CouponNumber = 124; 
 
 paymentEntity.CashPayments = new System.Data.Linq.EntitySet< DBML_Project.CashPayment>（）; 
 paymentEntity.CashPayments.Add（cashObj）; 
 
 paymentEntity.GiftCouponPayments = new System.Data.Linq.EntitySet< DBML_Project.GiftCouponPayment>（）; 
 paymentEntity.GiftCouponPayments.Add（giftCouponObj）; 
 
 Repository.InsertEntity（paymentEntity）; 
 Repository.SubmitChanges（）; 
} 
} 
  

资料库：

  public class LijosPaymentRepository：ILijosPaymentRepository 
 {
 public System.Data.Linq.DataContext MyDataContext {get;组; 
 
 public void InsertEntity（DBML_Project.Payment payment）
 {
 //插入实体
 MyDataContext.GetTable< DBML_Project.Payment>（）。InsertOnSubmit ）; 
} 
 
 public void SubmitChanges（）
 {
 MyDataContext.SubmitChanges（）; 
} 
} 
  




解决方案

对于@Lijo试图解决抽象方法的问题将会更好





我认为你可以对实现的CashPayment类型进行部分类您自己的IPayment接口，可以通过整个应用程序使用。此接口也可以在CreditCard付款：





示例：

  
 
 public interface IPayment 
 {
 int Id {get;组; } 
 int PaymentId {get;组; } 
 //其他付款特定属性或方法
} 
 
 public partial class CashPayment：IPayment 
 {
 public int Id 
 {
 get {return CashPaymentId; } 
 set {CashPaymentId = value; 
} 
 
 //其他属性
 
} 
 
公共部分类CreditCard付款：IPayment 
 {
 //更多代码... 
} 
 
  

您的EF上下文获得所有付款

  
 
 
公共部分类PaymentEntities //您的名称EF实体
 {
 public IQueryable AllPayments 
 {
 return this.CashPayment.Union（this.CreditCardPayment）; //这不好，只是一个例子。抽象类的方法在这里会更好。 
} 
 
 public void InsertPayment（IPayment payment）
 {
 this.AddObject（payment.GetType（）。Name，payment）; 
} 
} 
 
  




I have a database relationship as shown below. The domain objects are created based on LINQ to SQL ORM.

A payment comprises of Cash Payment and Gift Coupon Payments. Suppose the total amount of purchase is 550. It can be paid as following components

1 Gift Coupon Valued 300

1 Gift Coupon Valued 200

I Cash Currency Valued 50

I am inserting new payment records using the "InsertOnSubmit" function of ORM. The following code is working fine. However, if I the company is introducing a new payment component using credit card, I need to make changes to my "Payment" domain class. How do I make the payment class Open for Extension and Closed for Changes still using ORM?

Note: The Payment class has behaviors (E.g. GetTotalAmountCollected). I am trying to make the "Payment" class to satisfy OCP.

Note: There is a specific behavior for Coupon type. Is the Coupon issued date is less than 1/1/2000, it should not be used in calculation for Total Amount (i.e, CouponValue should be zero). Refer Refactoring code using Strategy Pattern also.

Note: I am using .Net 4.0

Reference:

1. Getting an error when using ObjectContext.AddObject with Entity Framework
2. Refactoring code using Strategy Pattern
3. Prefer composition over inheritance?
4. Code-first vs Model/Database-first
5. Strategy Pattern and Dependency Injection using Unity
6. C# Strategy Design Pattern by Delegate vs OOP
7. How to use the Strategy Pattern with C#?
8. Inheritance with EF Code First: Part 2 – Table per Type (TPT) http://weblogs.asp.net/manavi/archive/2010/12/28/inheritance-mapping-strategies-with-entity-framework-code-first-ctp5-part-2-table-per-type-tpt.aspx

C# Code:

public class PaymentAppService
{
    public RepositoryLayer.ILijosPaymentRepository Repository { get; set; }

    public void MakePayment()
    {
        DBML_Project.Payment paymentEntity = new DBML_Project.Payment();
        paymentEntity.PaymentID = 1;
        paymentEntity.PaymentType = "PurchaseP";

        DBML_Project.CashPayment cashObj = new DBML_Project.CashPayment();
        cashObj.CashPaymentID = 1;
        cashObj.CurrencyNumber = 123;
        cashObj.CurrencyValue = 100;

        DBML_Project.GiftCouponPayment giftCouponObj = new DBML_Project.GiftCouponPayment();
        giftCouponObj.GiftCouponPaymentID = 1;
        giftCouponObj.CouponValue = 200;
        giftCouponObj.CouponNumber = 124;

        paymentEntity.CashPayments = new System.Data.Linq.EntitySet<DBML_Project.CashPayment>();
        paymentEntity.CashPayments.Add(cashObj);

        paymentEntity.GiftCouponPayments = new System.Data.Linq.EntitySet<DBML_Project.GiftCouponPayment>();
        paymentEntity.GiftCouponPayments.Add(giftCouponObj);

        Repository.InsertEntity(paymentEntity);
        Repository.SubmitChanges();
    }
}

Repository:

public class LijosPaymentRepository : ILijosPaymentRepository
{
    public System.Data.Linq.DataContext MyDataContext { get; set; }

    public void InsertEntity(DBML_Project.Payment payment)
    {
        //Insert the entity
        MyDataContext.GetTable<DBML_Project.Payment>().InsertOnSubmit(payment);
    }

    public void SubmitChanges()
    {
        MyDataContext.SubmitChanges();
    }
}

解决方案

For the problem that @Lijo tries to solve the abstract approach would be better

I think you can make a partial class on the CashPayment type that implements your own IPayment interface, which can be used through the whole application. This interface can then also be on CreditCardPayment:

Example:

public interface IPayment
{
     int Id { get; set; }
     int PaymentId { get; set; }
     //Other payment specific properties or methods
}

public partial class CashPayment : IPayment
{
    public int Id 
    {
       get { return CashPaymentId ; }
       set { CashPaymentId = value; }
    }

    //Other properties

}

public partial class CreditCardPayment : IPayment 
{
   //more code ...
}

Something on your EF context to get all payments

public partial class PaymentEntities //The name of your EF entities
{
   public IQueryable AllPayments
   {
      return this.CashPayment.Union(this.CreditCardPayment); //This is not good, but just an example. The abstract class approach would be better here.
   }

    public void InsertPayment(IPayment payment)
    {
         this.AddObject(payment.GetType().Name, payment);
    }
}

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