ASP.NET Core MVC and Razor Pages Best Practices

This document outlines key best practices for developing applications using ASP.NET Core MVC and Razor Pages. Following these guidelines will lead to more maintainable, scalable, secure, and performant web applications.

Architecture Considerations

• Separation of Concerns: Adhere to the Model-View-Controller (MVC) pattern or the Page Model pattern in Razor Pages.
  • Models: Represent data and business logic.
  • Views/Razor Pages: Handle presentation logic.
  • Controllers/PageModels: Act as intermediaries, handling user input and orchestrating responses.
• Dependency Injection (DI): Leverage ASP.NET Core's built-in DI container for managing dependencies. This promotes loose coupling and testability. Register services in Startup.cs (or Program.cs in .NET 6+).
• Service Lifetimes: Understand and choose appropriate service lifetimes (Singleton, Scoped, Transient) based on your application's needs.
• Middleware Pipeline: Design your middleware pipeline carefully in Startup.cs (or Program.cs) to handle requests efficiently, especially for cross-cutting concerns like authentication, authorization, and logging.
• Configuration Management: Use the hierarchical configuration system (appsettings.json, environment variables, command-line arguments) to manage application settings.

Data Access

• Entity Framework Core (EF Core): Use EF Core for robust Object-Relational Mapping (ORM).
  • Migrations: Use EF Core Migrations to manage database schema changes systematically.
  • Asynchronous Operations: Always use asynchronous data access methods (e.g., ToListAsync(), SaveChangesAsync()) to prevent blocking threads and improve scalability.
  • Query Optimization: Be mindful of the queries generated by EF Core. Use features like Include() and ThenInclude() judiciously to avoid N+1 query problems. Consider projection to retrieve only necessary data.
• Repository Pattern: Consider implementing the Repository pattern for abstracting data access logic, further improving testability and maintainability.
• Connection Pooling: Ensure your data access libraries are configured for connection pooling to optimize database connection management.

UI Design & Rendering

MVC Views

• Razor Syntax: Write clean and organized Razor code. Keep presentation logic in views and delegate complex operations to the controller or view models.
• View Components: Use View Components for reusable UI fragments that require some data retrieval or business logic.
• Tag Helpers: Utilize Tag Helpers to create server-side HTML generation for common tasks, leading to cleaner HTML and reduced reliance on JavaScript for DOM manipulation.
• View Models: Pass strongly-typed view models to your views. This provides type safety and makes it easier to access data.

Razor Pages

• Page Models: Leverage Page Models to encapsulate page-specific logic, data, and handlers.
• Directory Structure: Organize Razor Pages logically within the Pages folder, mirroring your application's structure.
• Shared Layouts: Use `_Layout.cshtml` and `_ViewStart.cshtml` for consistent UI across your application.
• Partial Views/Pages: Use partial views or partial Razor Pages for reusable UI components within a page.

Security Best Practices

• Authentication & Authorization: Implement robust authentication and authorization mechanisms. Use ASP.NET Core Identity for user management and role-based access control.
• HTTPS: Enforce HTTPS for all communication.
• Cross-Site Scripting (XSS) Prevention: ASP.NET Core automatically encodes HTML output by default. Be cautious when rendering unencoded HTML. Use HtmlEncoder.Default.Encode() if absolutely necessary.
• Cross-Site Request Forgery (CSRF) Prevention: Use the built-in antiforgery token support by applying the [ValidateAntiForgeryToken] attribute to your POST actions and including the Razor tag helper <antiforgery> in your forms.
• Input Validation: Validate all user input on the server-side. Use data annotations (e.g., [Required], [StringLength]) and custom validation logic.
• Secure Sensitive Data: Avoid storing sensitive data (like passwords or API keys) in plain text. Use secret management tools like Azure Key Vault or user secrets during development.
• Rate Limiting & Throttling: Implement rate limiting to protect your application from abuse.
• Security Headers: Configure security-related HTTP headers (e.g., Strict-Transport-Security, Content-Security-Policy).

Performance Optimization

• Caching: Implement caching strategies at various levels (in-memory cache, distributed cache like Redis) to reduce database load and improve response times.
• Response Compression: Enable response compression (Gzip/Brotli) to reduce the size of data sent to the client.
• Lazy Loading vs. Eager Loading: Understand the trade-offs between lazy and eager loading in EF Core. Optimize queries to fetch only the necessary data.
• Minimize Payload Size: Optimize data returned to the client. Avoid sending unnecessary fields.
• Profiling: Use profiling tools (e.g., Application Insights, ANTS Performance Profiler) to identify performance bottlenecks.
• Background Tasks: Offload long-running or resource-intensive tasks to background services (e.g., using the IHostedService interface or Hangfire) to keep web requests quick.

Testing Strategies

• Unit Testing: Write comprehensive unit tests for your business logic, services, and controllers/PageModels. Mock dependencies using DI.
• Integration Testing: Test the interaction between different components of your application, including the web layer and data access. Use the WebApplicationFactory for integration tests.
• End-to-End (E2E) Testing: Use tools like Selenium or Playwright for simulating user interactions in a real browser.
• Test-Driven Development (TDD): Consider adopting TDD to guide development and ensure test coverage.

Deployment & Configuration

• Environment-Specific Configuration: Use separate configuration files (e.g., appsettings.Production.json) and environment variables for production settings.
• Logging: Implement robust logging using providers like Serilog or NLog. Configure log levels appropriately for different environments.
• Health Checks: Implement health check endpoints to monitor the status of your application and its dependencies.
• Containerization: Containerize your application using Docker for consistent deployment across environments.
• CI/CD: Establish a Continuous Integration and Continuous Deployment pipeline for automated builds, tests, and deployments.

API Development Guidelines

• RESTful Principles: Design APIs following RESTful principles, using appropriate HTTP methods (GET, POST, PUT, DELETE) and status codes.
• API Versioning: Implement API versioning to manage changes and avoid breaking existing clients.
• Data Transfer Objects (DTOs): Use DTOs to decouple your API contracts from your internal domain models.
• Swagger/OpenAPI: Integrate Swagger (Swashbuckle) to generate interactive API documentation.
• Error Handling: Provide consistent and informative error responses for API requests.