ActiveRecord SQLite Types

Custom ActiveRecord types for migrating from PostgreSQL to SQLite in Rails applications.

This gem provides drop-in replacements for PostgreSQL-specific data types that don't exist natively in SQLite, allowing you to migrate your Rails application from PostgreSQL to SQLite without changing your application code.

Installation

Add this line to your application's Gemfile:

gem "activerecord-sqlite-types"

And then execute:

bundle install

Available Types

IpAddress

Replaces PostgreSQL's inet type with a string representation that preserves IP address functionality.

Usage:

class User < ApplicationRecord
  attribute :current_sign_in_ip, SQLiteTypes::IpAddress.new
  attribute :last_sign_in_ip, SQLiteTypes::IpAddress.new
end

Migration:

class MigrateInetToString < ActiveRecord::Migration[7.0]
  def up
    change_column :users, :current_sign_in_ip, :string
    change_column :users, :last_sign_in_ip, :string
  end

  def down
    change_column :users, :current_sign_in_ip, :inet, using: 'current_sign_in_ip::inet'
    change_column :users, :last_sign_in_ip, :inet, using: 'last_sign_in_ip::inet'
  end
end

Array

Replaces PostgreSQL arrays with JSON-backed arrays, supporting querying via SQLite's JSON functions.

Supported subtypes: :integer, :string, :hash, :datetime

Usage:

class User < ApplicationRecord
  attribute :personality_traits, SQLiteTypes::Array.new(:string)
  attribute :favorite_numbers, SQLiteTypes::Array.new(:integer)
  attribute :nested_data, SQLiteTypes::Array.new(:integer, nested: true)
end

Migration:

class MigrateArrayToJson < ActiveRecord::Migration[7.0]
  def up
    change_column :users, :personality_traits, :json
    change_column :users, :favorite_numbers, :json
  end

  def down
    change_column :users, :personality_traits, :text, array: true, default: [], using: 'personality_traits::text[]'
    change_column :users, :favorite_numbers, :integer, array: true, default: [], using: 'favorite_numbers::integer[]'
  end
end

Querying arrays:

For array querying functionality, see Stephen Margheim's article on enhancing Rails SQLite array columns.

Interval

Replaces PostgreSQL's interval type with ISO8601 duration strings.

Usage:

class Event < ApplicationRecord
  attribute :duration, SQLiteTypes::Interval.new
end

Migration:

class MigrateIntervalToString < ActiveRecord::Migration[7.0]
  def up
    change_column :events, :duration, :string
  end

  def down
    change_column :events, :duration, :interval, using: 'duration::interval'
  end
end

Migration Strategy

The recommended approach for migrating from PostgreSQL to SQLite is incremental and reversible:

1. Prepare while still on PostgreSQL:

   • Add custom type declarations to your models
   • Run migrations to change column types (e.g., inet → string)
   • Test thoroughly - migrations are reversible!

2. Switch to SQLite:

   • Update database.yml to point to SQLite
   • Run your data migration script (e.g., pg-to-sqlite)
   • Run your test suite

3. Handle database constraints:

   • Drop PostgreSQL-specific constraints before switching
   • Add SQLite-compatible constraints after switching

For a detailed migration guide, see this presentation on migrating from PostgreSQL to SQLite.

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake test to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/wojtodzio/activerecord-sqlite-types.

License

The gem is available as open source under the terms of the MIT License.