Why migrations version the database in Ruby on Rails - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a migration that adds a new column.

Ruby on Rails

class AddAgeToUsers < ActiveRecord::Migration[6.0]
  def change
    add_column :users, :age, :[1]
  end
end

Drag options to blanks, or click blank then click option'

Ainteger

Bstring

Cboolean

Ddate

Attempts:

3 left

💡 Hint

Common Mistakes

Using a string type for age

Forgetting to specify the data type

The add_column method requires the data type of the new column. Here, integer is the correct type for an age.

2fill in blank

medium

Complete the code to run all pending migrations.

Ruby on Rails

rails [1]

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Adb:create

Bdb:rollback

Cdb:migrate

Ddb:seed

Attempts:

3 left

💡 Hint

Common Mistakes

Using db:create which only creates the database

Using db:seed which loads data

The command rails db:migrate runs all pending migrations to update the database schema.

3fill in blank

hard

Fix the error in the migration version declaration.

Ruby on Rails

class CreateProducts < ActiveRecord::Migration[1]
  def change
    create_table :products do |t|
      t.string :name
    end
  end
end

Drag options to blanks, or click blank then click option'

A6.0

B[5.2]

C(6.0)

D[6.0]

Attempts:

3 left

💡 Hint

Common Mistakes

Using parentheses instead of brackets

Omitting brackets entirely

The migration version must be specified in square brackets, like [6.0], to match the Rails version.

4fill in blank

hard

Fill both blanks to define a migration that removes a column.

Ruby on Rails

class RemoveEmailFromUsers < ActiveRecord::Migration[1]
  def change
    remove_column :users, :email, :[2]
  end
end

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A[6.1]

Bstring

Cinteger

D[5.0]

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong migration version

Wrong data type for email column

The migration version is specified as [6.1] and the data type of the removed column email is string.

5fill in blank

hard

Fill all three blanks to create a migration that renames a column.

Ruby on Rails

class RenameUsernameToLogin < ActiveRecord::Migration[1]
  def change
    rename_column :users, :[2], :[3]
  end
end

Drag options to blanks, or click blank then click option'

A[7.0]

Busername

Clogin

D[6.0]

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping old and new column names

Using wrong migration version

The migration version is [6.0]. The column username is renamed to login.