Contrasting DAOs and Repos: A Visual Exploration of Data Patterns in Ruby on Rails.

Repository vs DAO Patterns in Rails

A Comparative Analysis with Examples

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.

Example Usage:

Imagine a blogging platform. You have a Post model, and you want to abstract the data access.

class PostRepository

  def find_published
    Post.where(published: true)
  end

  def find_by_author(author_id)
    Post.where(author_id: author_id)
  end

end

Here, PostRepository provides specific methods for querying posts. It abstracts the ActiveRecord queries behind method calls, making the…