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POMaking Entity Class Closed for Changes
 

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    <p>I have a database relationship as shown below. The domain objects are created based on LINQ to SQL ORM. </p> <p>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</p> <pre><code>1 Gift Coupon Valued 300 1 Gift Coupon Valued 200 I Cash Currency Valued 50 </code></pre> <p><img src="https://i.stack.imgur.com/1ZxQH.jpg" alt="enter image description here"></p> <p>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 <strong>Open for Extension and Closed for Changes</strong> still using <strong>ORM</strong>?</p> <p>Note: The Payment class has <strong>behaviors</strong> (E.g. GetTotalAmountCollected). I am trying to make the "Payment" class to satisfy OCP.</p> <p>Note: There is a specific <strong>behavior</strong> 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 <a href="https://stackoverflow.com/questions/11435320/refactoring-code-using-strategy-pattern">Refactoring code using Strategy Pattern</a> also.</p> <p>Note: I am using <strong>.Net 4.0</strong></p> <p>Reference: </p> <ol> <li><a href="https://stackoverflow.com/questions/1174394/getting-an-error-when-using-objectcontext-addobject-with-entity-framework">Getting an error when using ObjectContext.AddObject with Entity Framework</a></li> <li><a href="https://stackoverflow.com/questions/11435320/refactoring-code-using-strategy-pattern">Refactoring code using Strategy Pattern</a></li> <li><a href="https://stackoverflow.com/questions/49002/prefer-composition-over-inheritance">Prefer composition over inheritance?</a> </li> <li><a href="https://stackoverflow.com/questions/5446316/ef-4-1-code-first-vs-model-database-first">Code-first vs Model/Database-first</a></li> <li><a href="https://stackoverflow.com/questions/1706056/strategy-pattern-and-dependency-injection-using-unity">Strategy Pattern and Dependency Injection using Unity</a></li> <li><a href="https://stackoverflow.com/questions/984050/c-sharp-strategy-design-pattern-by-delegate-vs-oop">C# Strategy Design Pattern by Delegate vs OOP</a></li> <li><a href="https://stackoverflow.com/questions/3449634/how-to-use-the-strategy-pattern-with-c">How to use the Strategy Pattern with C#?</a></li> <li>Inheritance with EF Code First: Part 2 – Table per Type (TPT) <a href="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" rel="nofollow noreferrer">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</a></li> </ol> <p>C# Code:</p> <pre><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&lt;DBML_Project.CashPayment&gt;(); paymentEntity.CashPayments.Add(cashObj); paymentEntity.GiftCouponPayments = new System.Data.Linq.EntitySet&lt;DBML_Project.GiftCouponPayment&gt;(); paymentEntity.GiftCouponPayments.Add(giftCouponObj); Repository.InsertEntity(paymentEntity); Repository.SubmitChanges(); } } </code></pre> <p>Repository:</p> <pre><code>public class LijosPaymentRepository : ILijosPaymentRepository { public System.Data.Linq.DataContext MyDataContext { get; set; } public void InsertEntity(DBML_Project.Payment payment) { //Insert the entity MyDataContext.GetTable&lt;DBML_Project.Payment&gt;().InsertOnSubmit(payment); } public void SubmitChanges() { MyDataContext.SubmitChanges(); } } </code></pre>
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    1. COSo LINQ to SQL, or Entity Framework and thus LINQ to Entities?
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    2. CO@Lijo - What do you mean by : Open for Extension and Closed for Changes still using ORM?
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    3. CO@bhuvin It is a statement from Open-Closed Principle. I cannot get rid of ORM to satisfy this principle.
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