ASP.NET Core – Implementing CQRS with MediatR – Part 3

The implementation of the CQRS pattern using MediatR in our ASP.NET Core project will simplify the logic and make our code more organized and easy to maintain. The separation of commands and queries allows for better readability and makes it easier to process and return information. The mediator library reduces coupling between different commands, making our code more robust and flexible. Overall, it’s a game-changer! 🚀

📝 Summary

In this weekly video tutorial, we will initiate the default implementation of our library. This implementation will contain the logic for using the application services to orchestrate and execute operations defined in the domain.

📊 Key Takeaways

The key takeaway from this implementation is to understand the principles that govern the implementation of commands and queries in CQRS with MediatR. It involves the separation of responsibilities between the command side that modifies the state and the query side that performs read operations.

🛠 Implementation of the Library

The library implementation will include complex commands and queries that interact with the application, domain, and infrastructure layers.

⚙️ Commands and Queries Categorization

We will implement commands under the ‘commands’ folder and queries under the ‘queries’ folder. This structural organization will aid in maintaining a clear separation of concerns within the application.

🔧 Implementing Commands

We need to decide whether specific commands should be implemented in the application or the domain layer. This decision is based on the complexity and scope of the commands.

Complexity of Commands

• Simple Commands:

  • Modify the state of the domain.
  • Can be implemented in the domain if they are straightforward.

• Complex Commands:

  • Involve multiple operations.
  • Should be implemented in the application layer.

📗 Command Handling

The handling of commands involves their execution and processing within the designated layers and handlers. This approach ensures a clean separation and efficient implementation of business rules and processes.

🚀 Implementing Mediator with CQRS

The MediatR library is used to facilitate the implementation of communicative patterns for handling commands and queries. Integrating the mediator into the project requires defining the instances, services, and dependencies necessary for its usage.

🗂 Mediator Registration

We need to register the mediator in the application layer to ensure its visibility and access throughout the project.

🌐 API Integration

The integration of the mediator within the API controllers helps in managing the flow of commands, improving readability, and favoring a decoupled structure.

✨ Conclusion

The seamless integration of commands, queries, and the MediatR library into the ASP.NET Core application provides a robust approach to handle data operations effectively.

📌 FAQ

Is the MediatR library mandatory for implementing CQRS?

• Although it is not mandatory, the MediatR library significantly simplifies the implementation and orchestration of commands and queries.

What role does the mediator play in managing requests and communicating between commands and queries?

• The mediator efficiently handles messages, notifications, and requests, streamlining the processing of commands and queries.

Has the separation of commands and queries facilitated the overall application development process?

• Yes, the separation of responsibilities has led to improved code organization and clarity in implementing various operations within the application.

With the successful implementation of commands, queries, and MediatR into the ASP.NET Core application, the quality and efficiency of data operations can be significantly improved.