Running and rolling back migrations in Ruby on Rails - Mini Project: Build & Apply

Running and Rolling Back Migrations in Rails

📖 Scenario: You are building a simple Rails app to manage a list of books. You need to create a database table for books and then learn how to run and rollback migrations to manage your database schema.

🎯 Goal: Create a migration to add a books table with title and author columns, run the migration to update the database, then rollback the migration to undo the changes.

📋 What You'll Learn

Create a migration file named create_books with title and author columns as strings

Run the migration using the correct Rails command

Rollback the last migration using the correct Rails command

💡 Why This Matters

🌍 Real World

Managing database schema changes safely is essential in real-world Rails applications to keep data consistent and allow easy updates.

💼 Career

Rails developers frequently create, run, and rollback migrations to evolve the database schema during development and deployment.

1

Create a migration file for books table

Generate a migration file named create_books that creates a books table with string columns title and author. Use the Rails generator command exactly as shown.

Ruby on Rails

# Run the Rails command to generate the migration file
# Your code here

Need a hint?

Use rails generate migration followed by the migration name and columns with types.

2

Run the migration to update the database

Run the migration to apply the changes to the database using the Rails command rails db:migrate.

Ruby on Rails

# Run the Rails command to migrate the database
# Your code here

Need a hint?

Use rails db:migrate to apply migrations.

3

Rollback the last migration

Rollback the last migration using the Rails command rails db:rollback to undo the changes made by the migration.

Ruby on Rails

# Run the Rails command to rollback the last migration
# Your code here

Need a hint?

Use rails db:rollback to undo the last migration.

4

Verify migration rollback

Add a command to check the current status of migrations using rails db:migrate:status to verify that the migration was rolled back.

Ruby on Rails

# Run the Rails command to check migration status
# Your code here

Need a hint?

Use rails db:migrate:status to see which migrations are applied.