How to remove a column using a Rails migration

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Learn how to effectively remove a column using a Rails migration in this step-by-step guide from the Full Stack Rails Mastery course.

This lesson is from Full Stack Rails Mastery.

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 We've switched to using Action Text for product descriptions. So we no longer need the description field in the products table. We can drop it by creating a Rails migration.

Generate the migration with this command:
rails g migration RemoveDescriptionFromProduct description:text

That will create a migration file under db/migrate with a name as follows:
db/migrate/YYYYMMDD162627_remove_description_from_product.rb

The migration looks like this:
class RemoveDescriptionFromProduct < ActiveRecord::Migration[7.1]
  def change
    remove_column :products, :description, :text
  end
end

Run the migration to drop the column:
bin/rails db:migrate

Note that this is a destructive change - you will lose any data stored in the dropped column. You can technically restore the column with a rollback command:
bin/rails db:rollback

However, that will only add an empty column back without any data.