Add Columns

This guide shows you how to add columns to existing tables using migrations.

Add a Single Column

class AddAvatarToUsers < CQL::Migration(5)
  def up
    schema.alter :users do
      add_column :avatar_url, String, null: true
    end
  end

  def down
    schema.alter :users do
      drop_column :avatar_url
    end
  end
end

Add Multiple Columns

class AddProfileFieldsToUsers < CQL::Migration(6)
  def up
    schema.alter :users do
      add_column :bio, String, null: true
      add_column :website, String, null: true
      add_column :location, String, null: true
    end
  end

  def down
    schema.alter :users do
      drop_column :bio
      drop_column :website
      drop_column :location
    end
  end
end

Add Column with Default

class AddActiveToUsers < CQL::Migration(7)
  def up
    schema.alter :users do
      add_column :active, Bool, default: true, null: false
    end
  end

  def down
    schema.alter :users do
      drop_column :active
    end
  end
end

Add Column with Index

class AddSlugToPosts < CQL::Migration(8)
  def up
    schema.alter :posts do
      add_column :slug, String, null: true
    end

    schema.alter :posts do
      create_index :idx_posts_slug, [:slug], unique: true
    end
  end

  def down
    schema.alter :posts do
      drop_index :idx_posts_slug
      drop_column :slug
    end
  end
end

Add Foreign Key Column

class AddCategoryToPosts < CQL::Migration(9)
  def up
    schema.alter :posts do
      add_column :category_id, Int64, null: true
      create_index :idx_posts_category_id, [:category_id]
      foreign_key [:category_id], references: :categories, references_columns: [:id], on_delete: :set_null
    end
  end

  def down
    schema.alter :posts do
      drop_foreign_key :fk_posts_category_id
      drop_index :idx_posts_category_id
      drop_column :category_id
    end
  end
end

Add Timestamp Columns

class AddTimestampsToPosts < CQL::Migration(10)
  def up
    schema.alter :posts do
      add_column :created_at, Time, null: true
      add_column :updated_at, Time, null: true
    end

    # Optionally set current time for existing records
    schema.exec("UPDATE posts SET created_at = NOW(), updated_at = NOW() WHERE created_at IS NULL")
  end

  def down
    schema.alter :posts do
      drop_column :created_at
      drop_column :updated_at
    end
  end
end

Add Column for Soft Deletes

class AddDeletedAtToUsers < CQL::Migration(11)
  def up
    schema.alter :users do
      add_column :deleted_at, Time, null: true
    end

    schema.alter :users do
      create_index :idx_users_deleted_at, [:deleted_at]
    end
  end

  def down
    schema.alter :users do
      drop_index :idx_users_deleted_at
      drop_column :deleted_at
    end
  end
end

Add Version Column for Locking

class AddVersionToUsers < CQL::Migration(12)
  def up
    schema.alter :users do
      add_column :version, Int32, default: 1, null: false
    end
  end

  def down
    schema.alter :users do
      drop_column :version
    end
  end
end

Update Model After Migration

After running the migration, update your model:

struct User
  # Existing properties...

  # New property
  property avatar_url : String?

  # Don't forget to update constructor if needed
  def initialize(@name : String, @email : String, @avatar_url : String? = nil)
  end
end

Verify Column Added

migrator.up

# Test the new column works
user = User.create!(name: "John", email: "[e-mail]", avatar_url: "/avatars/john.png")
user.avatar_url  # => "/avatars/john.png"

Related

• Create a Migration

• Create Indexes

• Migration DSL Reference