CQRS Design Pattern with MediaR is a practical guide for developers who want to build scalable, maintainable, and high-performance .NET applications using modern software architecture principles. The book introduces the CQRS (Command Query Responsibility Segregation) pattern and demonstrates how MediaR helps decouple application components while promoting clean architecture and better code organization.

Starting with the fundamentals of CQRS, the book explains why separating read and write operations improves scalability, maintainability, security, and overall application performance. Readers will also learn how MediaR acts as a mediator between controllers and business logic, reducing dependencies and making applications easier to test and extend.

The guide walks through creating a complete CQRS-based ASP.NET Core Web API using .NET 9, Entity Framework Core, FluentValidation, AutoMapper, SQL Server, Swagger UI, and JWT Authentication. It also covers project structure, repository implementation, database migrations, MVC integration, and application deployment, making it suitable for developers who want hands-on experience with enterprise application development.

Table of Contents

Introduction to CQRS

Learn the fundamentals of CQRS, understand how command and query operations are separated, explore clean architecture layers, and discover the benefits of scalability, security, maintainability, and performance optimization.

MediaR With CQRS

Understand how MediaR implements the Mediator pattern, simplifies communication between application layers, supports CQRS, and improves code organization using handlers, notifications, and pipeline behaviors.

CQRS Project Creation

Build a CQRS-based ASP.NET Core Web API from scratch by setting up the development environment, installing required packages, configuring Entity Framework Core, creating repositories, and running database migrations.

Create Controller API with Swagger UI

Learn how to implement MediaR handlers, commands, and queries in the application layer while exposing REST APIs with Swagger UI for complete CRUD operations.

Secure Web API with JWT Token Authentication

Learn how to secure your CQRS-based Web API using JWT authentication, protect endpoints, and implement role-based authorization for secure access control.

Migration of Database in CQRS Pattern

Understand how Entity Framework Core migrations are used to create, update, and maintain the database schema within a CQRS application while keeping the data layer synchronized with the domain model.

.NET Core MVC Web Application

Learn how to integrate an ASP.NET Core MVC application with a CQRS-based backend and consume APIs to build a clean, responsive web application.

Deployment of .NET Core Application

Complete the development lifecycle by deploying the finished CQRS application, preparing it for production, and understanding the essential deployment workflow.