Passing data to partials in Ruby on Rails - Mini Project: Build & Apply

Passing Data to Partials in Rails

📖 Scenario: You are building a simple Rails app that shows a list of books. Each book has a title and an author. You want to display each book using a reusable partial view.

🎯 Goal: Create a Rails partial to display a book's title and author. Pass each book's data from the main view to the partial using local variables.

📋 What You'll Learn

Create a list of books as an array of hashes in the view

Create a variable to hold the total number of books

Use a for loop with variables book to iterate over the books array

Render a partial called _book.html.erb passing the current book as a local variable

In the partial, display the book's title and author using the passed local variable

💡 Why This Matters

🌍 Real World

Passing data to partials is common in Rails apps to reuse view code and keep templates clean and organized.

💼 Career

Understanding how to pass data to partials is essential for Rails developers to build maintainable and scalable web applications.

1

Create the books data array

Create a variable called books that is an array of hashes with these exact entries: { title: 'The Hobbit', author: 'J.R.R. Tolkien' }, { title: '1984', author: 'George Orwell' }, and { title: 'Pride and Prejudice', author: 'Jane Austen' }.

Ruby on Rails

# Create the books array with the specified hashes
# Your code here

Need a hint?

Use square brackets [] to create an array and curly braces {} for each book hash.

2

Create a variable for total books count

Create a variable called total_books and set it to the length of the books array using books.length.

Ruby on Rails

books = [
  { title: 'The Hobbit', author: 'J.R.R. Tolkien' },
  { title: '1984', author: 'George Orwell' },
  { title: 'Pride and Prejudice', author: 'Jane Austen' }
]
# Create total_books variable with the length of books
# Your code here

Need a hint?

Use the .length method on the array to get the count.

3

Render the partial for each book with local variable

Use a for loop with variable book to iterate over books. Inside the loop, render the partial 'book' passing the current book as a local variable named book using render partial: 'book', locals: { book: book }.

Ruby on Rails

books = [
  { title: 'The Hobbit', author: 'J.R.R. Tolkien' },
  { title: '1984', author: 'George Orwell' },
  { title: 'Pride and Prejudice', author: 'Jane Austen' }
]
total_books = books.length

# Use a for loop to render the 'book' partial for each book with locals
# Your code here

Need a hint?

Use the for loop syntax and the render method with partial and locals options.

4

Create the partial to display book details

In the partial file _book.html.erb, use the local variable book to display the book's title inside an <h3> tag and the author inside a <p> tag. Use <%= book[:title] %> and <%= book[:author] %> respectively.

Ruby on Rails

Need a hint?

Use ERB tags <%= %> to output the book's title and author from the local variable.