Scopes for reusable queries in Ruby on Rails - Mini Project: Build & Apply

Scopes for reusable queries

📖 Scenario: You are building a simple blog application where you want to easily find published posts and posts created recently.

🎯 Goal: Create reusable query scopes in the Post model to filter published posts and recent posts.

📋 What You'll Learn

Create a Post model with title, body, published (boolean), and created_at attributes

Add a scope called published that returns only posts where published is true

Add a scope called recent that returns posts created within the last 7 days

Use ActiveRecord query methods to define the scopes

💡 Why This Matters

🌍 Real World

Scopes help keep your Rails code clean and DRY by reusing common queries across your app.

💼 Career

Understanding scopes is essential for Rails developers to write maintainable and efficient database queries.

1

Create the Post model with attributes

Create a Post model class that inherits from ApplicationRecord with attributes title, body, published, and created_at.

Ruby on Rails

class Post < ApplicationRecord
  # Your code here
end

Need a hint?

Define the model class and mention the attributes as comments for clarity.

2

Add a scope for published posts

Add a scope called published in the Post model that returns posts where published is true using where(published: true).

Ruby on Rails

class Post < ApplicationRecord
  # Attributes: title:string, body:text, published:boolean, created_at:datetime

  # Your code here
end

Need a hint?

Use scope :published, -> { where(published: true) } to define the scope.

3

Add a scope for recent posts

Add a scope called recent in the Post model that returns posts created within the last 7 days using where('created_at >= ?', 7.days.ago).

Ruby on Rails

class Post  { where(published: true) }

  # Your code here
end

Need a hint?

Use scope :recent, -> { where('created_at >= ?', 7.days.ago) } to define the recent posts scope.

4

Use the scopes in a query

Write a query using the Post model that chains the published and recent scopes to get posts that are published and created within the last 7 days.

Ruby on Rails

class Post  { where(published: true) }
  scope :recent, -> { where('created_at >= ?', 7.days.ago) }
end

# Your code here to query published and recent posts

Need a hint?

Chain the scopes by calling Post.published.recent and assign it to posts.