Nested attributes in Ruby on Rails - Mini Project: Build & Apply

Nested Attributes in Rails

📖 Scenario: You are building a simple Rails app to manage books and their authors. Each book can have one author. You want to create and update books along with their authors in one form.

🎯 Goal: Build a Rails model setup using nested attributes so you can create and update a Book and its associated Author together.

📋 What You'll Learn

Create a Book model with a title attribute

Create an Author model with a name attribute

Set up a one-to-one association between Book and Author

Enable nested attributes for Author inside Book

Permit nested attributes in the BooksController

💡 Why This Matters

🌍 Real World

Nested attributes let you edit related data together, like a book and its author, in one form. This is common in content management systems and admin panels.

💼 Career

Understanding nested attributes is important for Rails developers to build efficient forms and maintain clean code when dealing with related models.

1

Create Book and Author models with association

Create a Book model with a title:string and an Author model with a name:string. Set up a one-to-one association where Book has_one :author and Author belongs_to :book.

Ruby on Rails

# Create Book and Author models with association
# Your code here

Need a hint?

Use has_one :author in Book and belongs_to :book in Author.

2

Enable nested attributes for Author in Book model

In the Book model, add accepts_nested_attributes_for :author to allow nested attributes for the associated author.

Ruby on Rails

class Book < ApplicationRecord
  has_one :author
  # Add nested attributes acceptance here
  # Your code here
end

class Author < ApplicationRecord
  belongs_to :book
end

Need a hint?

Add accepts_nested_attributes_for :author inside the Book class.

3

Permit nested author attributes in BooksController

In the BooksController, update the book_params method to permit author_attributes with name. Use params.require(:book).permit(:title, author_attributes: [:name]).

Ruby on Rails

class BooksController < ApplicationController
  private

  def book_params
    # Permit title and nested author attributes
    # Your code here
  end
end

Need a hint?

Permit author_attributes with name inside book_params.

4

Add author fields to Book form

In the books/_form.html.erb partial, add nested fields for author using fields_for :author. Inside it, add a text field for name with label Author Name.

Ruby on Rails

  
  

  
    
    # Your code here
  

  

Need a hint?

Use fields_for :author and inside it add label and text field for name.