# Create table migration
class CreateUsers < ActiveRecord::Migration[7.0]
def change
create_table :users do |t|
t.string :email, null: false, index: { unique: true }
t.string :name, null: false
t.string :password_digest
t.string :role, default: 'user'
t.integer :posts_count, default: 0
t.timestamp :last_login_at
t.timestamps
end
add_index :users, :email
add_index :users, :role
end
end
# Add column migration
class AddAvatarToUsers < ActiveRecord::Migration[7.0]
def change
add_column :users, :avatar_url, :string
add_column :users, :bio, :text
end
end
# Remove column
class RemoveAvatarFromUsers < ActiveRecord::Migration[7.0]
def change
remove_column :users, :avatar_url, :string
end
end
# Rename column
class RenameUserNameToFullName < ActiveRecord::Migration[7.0]
def change
rename_column :users, :name, :full_name
end
end
# Change column type
class ChangeUserBioToText < ActiveRecord::Migration[7.0]
def change
change_column :users, :bio, :text
end
end
# Add foreign key
class AddUserIdToPosts < ActiveRecord::Migration[7.0]
def change
add_reference :posts, :user, null: false, foreign_key: true, index: true
end
end
# Custom index
class AddCompoundIndexToPosts < ActiveRecord::Migration[7.0]
def change
add_index :posts, [:user_id, :status]
add_index :posts, [:status, :created_at], where: "status = 'published'"
# Full-text search index (PostgreSQL)
add_index :posts, :content, using: :gin,
opclass: :gin_trgm_ops # Requires pg_trgm extension
end
end
# Data migration
class MigrateUserRoles < ActiveRecord::Migration[7.0]
def up
User.where(admin: true).update_all(role: 'admin')
User.where(admin: false).update_all(role: 'user')
remove_column :users, :admin
end
def down
add_column :users, :admin, :boolean, default: false
User.where(role: 'admin').update_all(admin: true)
end
end
# Reversible block for complex operations
class AddStatusToUsers < ActiveRecord::Migration[7.0]
def change
add_column :users, :status, :string
reversible do |dir|
dir.up do
User.update_all(status: 'active')
end
dir.down do
# Cleanup logic
end
end
change_column_null :users, :status, false
end
end
# Add constraint
class AddConstraintToUsers < ActiveRecord::Migration[7.0]
def change
add_check_constraint :users, "age >= 18", name: "users_age_check"
# Uniqueness constraint
add_index :users, :email, unique: true
end
end
# Create join table
class CreateJoinTableUsersGroups < ActiveRecord::Migration[7.0]
def change
create_join_table :users, :groups do |t|
t.index :user_id
t.index :group_id
t.timestamps
end
end
end
# Enable PostgreSQL extension
class EnablePgExtensions < ActiveRecord::Migration[7.0]
def change
enable_extension 'uuid-ossp'
enable_extension 'pg_trgm' # Trigram matching for LIKE queries
enable_extension 'hstore' # Key-value storage
end
end
# Create enum type (PostgreSQL)
class CreatePostStatusEnum < ActiveRecord::Migration[7.0]
def up
execute <<-SQL
CREATE TYPE post_status AS ENUM ('draft', 'published', 'archived');
SQL
add_column :posts, :status, :post_status, default: 'draft'
end
def down
remove_column :posts, :status
execute <<-SQL
DROP TYPE post_status;
SQL
end
end
