Strategy Design Pattern in C#

This project demonstrates the implementation of the Strategy Design Pattern in C#. The Strategy Pattern is used to define a family of algorithms, encapsulate each one, and make them interchangeable. This pattern lets the algorithm vary independently from the clients that use it.

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Project Structure

Entities

• Order: Represents an order with properties such as OrderId, Amount, and OrderType.
• OrderType: Enum representing different payment types (e.g., CreditCard, Paypal, Bitcoin, and Cash).

Services

• Without Strategy:

  • Bad_OrderService: Processes payments using a switch statement, violating the Open/Closed Principle. Adding new payment types requires modifying the existing code.
  • Endpoints: /api/withoutStrategy showcases the complexity of this approach.

• With Strategy:

  • Strategy Interface:
    • IPaymentStrategy: Defines the interface for all payment strategies.
  • Concrete Strategies:
    • CreditCardPayment, PayPalPayment, BitcoinPayment, and CashPayment: Implementations of different payment strategies.
  • Factory:
    • PaymenyStrategyFactory: Returns the appropriate payment strategy based on the OrderType.
  • Context:
    • PaymentContext: Encapsulates a payment strategy and delegates payment execution.
  • Dynamic Registration:
    • PaymentStrategyRegistery: Allows dynamic registration of new payment types.
  • Endpoints:
    • /api/Strategy: Demonstrates payment processing with the Strategy Pattern.
    • /api/Strategy/Better: Illustrates the enhanced approach with dynamic strategy registration.

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Features

Without Strategy

• Payment processing is handled using a switch statement in Bad_OrderService.
• Adding new payment types requires modifying the service, increasing the risk of errors and maintenance challenges.

With Strategy

• Payment processing logic is encapsulated in separate strategy classes.
• Adheres to the Open/Closed Principle:
  • Adding new payment types is as simple as creating a new class and registering it.
• Dynamic strategy registration allows runtime flexibility.

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Why Use the Strategy Pattern?

1. Decoupling: Separates the algorithm (payment processing) from the client (order service).
2. Extensibility: New payment types can be added without modifying existing code.
3. Testability: Each strategy can be independently tested.
4. Flexibility: Strategies can be registered dynamically at runtime.

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API Endpoints

Without Strategy

• GET /api/withoutStrategy:
  Fetches payment results processed using Bad_OrderService.

With Strategy

• GET /api/Strategy:
  Fetches payment results processed using the Strategy Pattern.

• GET /api/Strategy/Better:
  Fetches payment results processed using dynamically registered strategies.

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Example Requests

Without Strategy

GET /api/withoutStrategy
Response:

[
  {
    "orderId": 1,
    "amount": 100.0,
    "orderType": "CreditCard",
    "result": "Paid 100.0 using Credit Card for Order 1 ."
  }
]

With Strategy

GET /api/Strategy
Response:

[
  {
    "orderId": 1,
    "amount": 100.0,
    "orderType": "CreditCard",
    "result": "Paid 100.0 using Credit Card for Order 1 ."
  },
  {
    "orderId": 4,
    "amount": 400.0,
    "orderType": "Cash",
    "result": "Paid 400.0 using cash for Order 4"
  }
]

GET /api/Strategy/Better
Response:

[
  {
    "orderId": 1,
    "amount": 100.0,
    "orderType": "CreditCard",
    "result": "Paid 100.0 using Bitcoin for Order 1 ." // Dynamically registered strategy.
  }
]

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How to Run the Project

Prerequisites:

• .NET 8.0 or higher.
• Visual Studio or any C# IDE.

Steps:

1. Clone the repository:

   git clone <repository-url>

2. Navigate to the project directory.
3. Run the application:

   dotnet run

4. Use Swagger UI to test the endpoints:
   • Access Swagger at: https://localhost:<port>/swagger.

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Technologies Used

• C#
• ASP.NET Core Minimal API
• Swagger for API documentation

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Resources

Video Tutorials:

• YouTube:بررسی Strategy Design Pattern و موارد استفاده از آن

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Credits

Develop By AliCharper

Refactor by Mohammad.
Feel free to reach out for feedback or collaboration!