Mongoid Sequence

Mongoid Sequence allows you to specify fields to behave like a sequence number (exactly like the "id" column in conventional SQL flavors).

Credits

This gem was inspired by a couple of gists by masatomo and ShogunPanda.

Usage

Include Mongoid::Sequence in your class and call sequence(:field).

Like this:

class Sequenced
	include Mongoid::Document
	include Mongoid::Sequence

	field :my_sequence, :type => Integer
	sequence :my_sequence
end

s1 = Sequenced.create
s1.sequence #=> 1

s2 = Sequenced.create
s2.sequence #=> 2 # and so on

It is possible to add an additional discriminator to the sequence (e.g. a tenant id)

class Sequenced
	include Mongoid::Document
	include Mongoid::Sequence

  field :my_sequence, :type => Integer
  belongs_to :organization

	sequence :my_sequence, prefix: :organization_id
end

If you have an embedded document, you don't have worrying about fake increment inside each child, mongoid-secuence will recognize this association and segregate the count per each child

class Sequenced
	include Mongoid::Document
	include Mongoid::Sequence

  field :my_sequence, :type => Integer

  embedded_in :parent

	sequence :my_sequence
end

If you have an inheritance relation and you want to keep the sequence associated with one of your parents, you can specify what ancestors level you want using the parent_level option, below scenario will keep the sequence called parent_my_sequence sequence for Child instances

class Parent
	include Mongoid::Document
	include Mongoid::Sequence

  field :my_sequence, :type => Integer
end

class Child
	include Mongoid::Document
	include Mongoid::Sequence

  sequence :my_sequence, parent_level: 1
end

It's also possible to make the id field behave like this:

class Sequenced
	include Mongoid::Document
	include Mongoid::Sequence

	sequence :_id
end

s1 = Sequenced.create
s1.id #=> 1

s2 = Sequenced.create
s2.id #=> 2 # and so on

Consistency

Mongoid::Sequence uses the atomic findAndModify command, so you shouldn't have to worry about the sequence's consistency.

Installation

Just add it to your projects' Gemfile:

gem "mongoid-sequence"

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Copyright © 2017 Gonçalo Silva, Johan Tique released under the MIT license