How CQRS Can Simplify Your Ruby on Rails Application?
Snippets of Code is an engineering journal that documents technical experiments and projects.
Are you struggling with complex Ruby on Rails codebases?
Have you considered that managing read and write operations in an ActiveRecord model can be the coupling problem that companies like Shopify, Github, Gusto, Doximity, and Zendesk are still battling? You’re not alone.
The Command Query Responsibility Segregation (CQRS) pattern might be your solution. This approach splits your system into components that handle specific tasks—commands or queries—allowing for a more streamlined and straightforward system to understand.
CQRS divides the management of data into commands and queries.
Commands handle write operations, while queries manage read operations. This separation allows you to optimize each component independently, resulting in better performance and easier scaling.
If you think someone will benefit from this content, please share.
For instance, if your application needs to handle a high volume of reads, you can scale just the read component without affecting the write operations.
Read models, an integral part of CQRS, offer several advantages:
Improved Performance: You can fine-tune performance for specific queries by isolating read operations.
Reduced Query Complexity: Simplified data retrieval processes mean less complex SQL queries.
Scalability: Read models can be created or adjusted to fit new use cases without impacting the primary data model.
Even though using read models can introduce data duplication, it’s often not an issue. This duplication helps quickly retrieve data tailored to specific needs, enhancing overall efficiency.
If you are enjoying the learning journal, please ❤️
Incorporating CQRS into systems built with frameworks like Ruby on Rails can be challenging, primarily when ActiveRecord handles both reads and writes in one component.
The key is to separate data structure from business rules, which might require reworking some parts of your system. Be mindful of eventual consistency, where changes may not be immediately visible across all parts of your system, potentially causing referential integrity issues.
Implementing CQRS can significantly enhance your system’s performance and scalability.
By separating read and write operations, you can simplify management and optimize data handling.
💻 👓
To create a read model in Ruby on Rails using Rails Event Store, you typically implement an event handler that builds a denormalized data model based on events published to the event store.
Define the Domain Event
Create the Read Model
Next, create an ActiveRecord model that will serve as the read model. This model will store the quiz progress.
Implement the Event Handler
Now, implement an event handler that listens for `QuestionAnswered` events and updates the read model accordingly:
Subscribe to Events
Finally, subscribe the event handler to the `QuestionAnswered` event in your Rails initializer:
Querying the Read Model
You can now query the `QuizProgress` model to retrieve data for display in your application:
The process involves defining domain events, creating an ActiveRecord model for the read model, implementing an asynchronous event handler to update this model, and subscribing to events. This approach allows for efficient data retrieval tailored to UI needs while leveraging the power of event sourcing.