comprehensive EF Core + .NET Core coding and architecture practice roadmap

1. EF Core: Core CRUD & Mapping Practice

Goal: Master EF Core fundamentals and database mapping.

Tasks:

1. Create a .NET Core Web API project.
2. Define DbContext and models with:
• Data annotations
• Fluent API mapping
3. Implement basic CRUD for Employee, Project, Invoice.
4. Practice relationship mapping:
• One-to-one
• One-to-many
• Many-to-many
5. Explore shadow properties & computed columns.
6. Use AsNoTracking() for read-only queries to test performance.

Mini Coding Exercise:

• Build Employee-Project management API with CRUD.
• Test queries with tracking vs no-tracking and measure performance.

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2. EF Core: Advanced Features & Performance

Goal: Optimize queries and understand advanced EF Core behavior.

Tasks:

1. Query Optimization
• Include(), ThenInclude() for eager loading.
• Explicit loading vs lazy loading.
• Projection with Select() for DTOs.
2. Batch Operations
• ExecuteUpdate, ExecuteDelete
3. Performance Tools
• ToQueryString() to see generated SQL.
• Logging SQL queries for profiling.
• Index creation via Fluent API.
4. Caching / No-Tracking
• Read-heavy APIs → AsNoTracking()
• Optional: Redis caching for frequent queries.

Mini Coding Exercise:

• Create a dashboard API for invoices that aggregates data.
• Optimize queries using projections and no-tracking.

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3. Security in EF Core & .NET Core APIs

Goal: Learn how to secure data access and prevent vulnerabilities.

Tasks:

1. Authentication & Authorization
• Implement JWT Authentication.
• Role-based access: Admin vs User.
2. Prevent SQL Injection
• EF Core parameterized queries are safe by default.
• Dapper: always use parameters, never string interpolation.
3. Data Protection
• Hash passwords (BCrypt or ASP.NET Identity).
• Use DTOs to avoid exposing sensitive fields.

Mini Coding Exercise:

• Implement login/register endpoints.
• Protect invoice APIs: only owners or admins can access.
• Attempt injection with raw SQL (simulate attack) → see EF Core safe handling.

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4. Dapper: Micro-ORM Practice

Goal: Learn when to use Dapper vs EF Core, and how to integrate both.

Tasks:

1. Install Dapper and connect to SQL Server.
2. Write parameterized queries for:
• Select
• Insert
• Update
• Delete
3. Compare performance with EF Core for heavy read scenarios.
4. Combine Dapper with EF Core in same app:
• Use EF Core for entity management
• Use Dapper for high-performance reporting queries

Mini Coding Exercise:

• Create a report API that fetches top 10 invoices per client using Dapper.
• Measure execution time vs EF Core.

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5. Application Architecture & Patterns

Goal: Design scalable, maintainable apps.

Tasks:

1. Design Patterns
• Repository + Unit of Work with EF Core
• CQRS with MediatR
• Factory / Strategy (e.g., Payment Gateway selection)
2. Layering
• Separate Projects: API / Core / Infrastructure
• Dependency Injection for services and repositories
3. Exception Handling
• Global exception middleware
• Logging with Serilog or NLog

Mini Coding Exercise:

• Refactor invoice app using Repository + Unit of Work.
• Implement CQRS for Invoice creation vs Invoice reporting.

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6. Advanced EF Core: Migration & Maintenance

Tasks:

1. Create migrations, update database.
2. Seed initial data programmatically.
3. Handle multiple DbContexts in same app.
4. Soft delete vs hard delete patterns.

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7. Testing & CI/CD

Goal: Ensure code correctness and maintainability.

Tasks:

1. Unit test repositories with InMemoryDbContext.
2. Integration tests for API endpoints.
3. Automate database migration in CI/CD pipeline.
4. Performance tests: measure query execution, EF vs Dapper.

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8. Mini Project: Full EF Core + Dapper + Secure API

Scenario: Invoice Management System

• Entities: Employee, Project, Client, Invoice, Payment
• Features:
• CRUD for all entities (EF Core)
• Reporting endpoints (Dapper for heavy reads)
• JWT-based Auth + Role-based access
• Optimized queries, no-tracking where applicable
• CQRS for Invoice Creation vs Invoice Reporting
• Pagination + Filtering + Sorting
• Logging + Exception handling

Bonus: Generate PDF reports using invoice data.

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✅ Extra Focus Areas for Coding Interviews

• EF Core vs Dapper differences & trade-offs
• Tracking vs NoTracking
• Eager vs Lazy loading
• Raw SQL in EF Core
• Performance pitfalls: N+1 queries, large data fetch
• Security: JWT, SQL Injection, Sensitive data exposure
• Clean architecture & dependency injection