CQRS and MediatR in ASP.NET Core - Ultimate Guide!

Building Decoupled & Scalable .NET Systems

Of the several design patterns available, CQRS is one of the most commonly used patterns that help architect solutions that follow clean architecture principles.

CQRS, or Command Query Responsibility Segregation helps you build super clean and scalable systems with ease.

It is a software architectural pattern that separates the read and write operations of a system into two different parts. In a CQRS architecture, the write operations (commands) and read operations (queries) are handled separately, using different models optimized for each operation. This separation can lead to simpler and more scalable architectures, especially in complex systems where the read and write patterns differ significantly.

Here is a diagrammatic representation.

PROS

  • Streamlined Data Transfer Objects

  • Scalability

  • Performance Enhancement

  • Improved Concurrency and Parallelism

CONS

  • Increased Complexity and Code Volume

Here is the folder structure that we are going to design, and implement CQRS using the MediatR library.

I will build an ASP.NET Core 8 Web API that performs CRUD Operations demonstrating this awesome pattern!

We will explore CQRS implementation and its definition, the Mediator pattern, and the MediatR Library. We’ll also cover Entity Framework Core implementation, Vertical Slice Architecture, and more. Further, we will also discuss Request/Response patterns as well as the Notifications in MediatR.

Next week, we will discuss Pipeline Behavior in MediatR and combine FluentValidation, IExceptionHandler, and CQRS to build a durable system!

Thanks, and stay connected!

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