ar-sequence

Add support for PostgreSQL's SEQUENCE on ActiveRecord migrations.

Installation

gem install ar-sequence

Or add the following line to your project's Gemfile:

gem "ar-sequence"

Usage

To create a SEQUENCE, just use the method create_sequence.

class CreateUsers < ActiveRecord::Migration[5.2]
 def up
   create_sequence :position
 end

 def down
   drop_sequence :position
 end
end

You can also specify the initial value and increment:

create_sequence :position, increment: 2
create_sequence :position, start: 100

To define a column that has a sequence as its default value, use something like the following:

class CreateThings < ActiveRecord::Migration[5.2]
  def change
    create_sequence :position

    create_table :things do |t|
      t.text :name

      # PostgreSQL uses bigint as the sequence's default type.
      # Use a block to specify the default value on migrations.
      t.bigint :position,
                null: false,
                default: -> { "nextval('position')" }

      t.timestamps
    end
  end
end

This gem also adds a few helpers to interact with SEQUENCEs.

# Advance sequence and return new value
ActiveRecord::Base.nextval("position")

# Return value most recently obtained with nextval for specified sequence.
ActiveRecord::Base.currval("position")

# Set sequence's current value
ActiveRecord::Base.setval("position", 1234)

Maintainer

• Nando Vieira

Contributors

• https://github.com/fnando/ar-sequence/contributors

Contributing

For more details about how to contribute, please read https://github.com/fnando/ar-sequence/blob/main/CONTRIBUTING.md.

License

The gem is available as open source under the terms of the MIT License. A copy of the license can be found at https://github.com/fnando/ar-sequence/blob/main/LICENSE.md.

Code of Conduct

Everyone interacting in the ar-sequence project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.