Changing column types in Ruby on Rails - Mini Project: Build & Apply

Changing column types in Rails migrations

📖 Scenario: You are working on a Rails app that manages a library. You need to update the database to change the data type of a column to better fit the data it will hold.

🎯 Goal: Create a Rails migration to change the data type of the published_year column in the books table from string to integer.

📋 What You'll Learn

Create a migration file named ChangePublishedYearTypeInBooks

Use the change_column method to change published_year from string to integer

Ensure the migration is reversible

Use the correct Rails migration syntax

💡 Why This Matters

🌍 Real World

Changing column types is common when app requirements evolve and data needs to be stored differently.

💼 Career

Rails developers often write migrations to update database schemas safely and maintainably.

1

Create the migration class

Create a migration class named ChangePublishedYearTypeInBooks that inherits from ActiveRecord::Migration[7.0].

Ruby on Rails

class ChangePublishedYearTypeInBooks < ActiveRecord::Migration[7.0]
  # Your code here
end

Need a hint?

Start by defining a class with the exact name and inheritance shown.

2

Add the change method

Inside the ChangePublishedYearTypeInBooks class, add a change method definition.

Ruby on Rails

class ChangePublishedYearTypeInBooks < ActiveRecord::Migration[7.0]
  def change
    # Your code here
  end
end

Need a hint?

The change method is where you put migration instructions.

3

Use change_column to modify the column type

Inside the change method, use change_column to change the published_year column in the books table from string to integer.

Ruby on Rails

class ChangePublishedYearTypeInBooks < ActiveRecord::Migration[7.0]
  def change
    # Your code here
  end
end

Need a hint?

Use change_column :books, :published_year, :integer inside the change method.

4

Complete the migration class

Ensure the migration class is complete with the change method containing the change_column call and properly closed with end.

Ruby on Rails

class ChangePublishedYearTypeInBooks < ActiveRecord::Migration[7.0]
  def change
    change_column :books, :published_year, :integer
  end
end
# Migration complete

Need a hint?

Check that all parts of the class and method are present and closed properly.