Repository vs DAO Patterns in Rails
Article based on a comment from a previous article: click here
In Ruby on Rails, understanding design patterns is crucial for creating maintainable and scalable applications. The Repository and Data Access Object (DAO) patterns are widely used for data access layers, but they serve different purposes, especially considering Rails’ robust Object-Relational Mapping (ORM) system, ActiveRecord. Let’s explore these patterns, focusing on how they integrate with Rails’ ORM.
Repository Pattern in Rails
The Repository pattern abstracts the data layer, providing a collection-like interface for accessing domain entities. In Rails, this means abstracting ActiveRecord models, which allows for more flexibility and easier testing.
Imagine a blogging platform. You have a Post model, and you want to abstract the data access.
Here, PostRepository provides specific methods for querying posts. It abstracts the ActiveRecord queries behind method calls, making the calling code cleaner and more readable.
DAO Pattern in Rails
The DAO pattern is a more granular approach compared to the Repository. It acts as a proxy for more complex queries or insertions, tightly coupling with the model but offering more control over database interactions.
Continuing with the blogging platform example, you might need complex queries for the Post model.
@post = post
Audit.create!(post_id: @post.id, action: "saved")
# A complex SQL query
In this case, PostDAO is closely tied to the Post model, handling complex transactions and queries that go beyond simple CRUD operations.