Noid::Rails

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What is noid-rails?

This gem mints identifiers for models in your Rails-based application with opaque Noid-based identifiers.

This gem depends only upon Rails, not on ActiveFedora

Product Owner & Maintenance

noid-rails was a Core Component of the Samvera Community. Given a decline in available labor required for maintenance, this project no longer has a dedicated Product Owner. The documentation for what this means can be found here.

Product Owner

Vacant

Until a Product Owner has been identified, we ask that you please direct all requests for support, bug reports, and general questions to the #dev Channel on the Samvera Slack.

Table of Contents

• Installation

• Usage

  • Minting and validating identifiers

  • ActiveFedora integration

    • Identifier/URI translation

  • Overriding default behavior

    • Use database-based minter state
    • Identifier template
    • Custom minters

• Help

• Acknowledgments

Installation

Add this line to your application's Gemfile:

gem 'noid-rails'

And then execute:

$ bundle install

Or install it yourself via:

$ gem install noid-rails

Usage

Minting and validating identifiers

Mint a new Noid:

noid_service = Noid::Rails::Service.new
noid = noid_service.mint

This creates a Noid with the default identifier template, which you can override (see below). Now that you have a service object with a template, you can also use it to validate identifiers to see if they conform to the template:

noid_service.valid? 'xyz123foobar'
> false

ActiveFedora integration

To get ActiveFedora to automatically call your Noid service whenever a new ActiveFedora object is saved, include the Noid::Rails::Model, e.g.:

# app/models/my_object.rb
require 'noid-rails'

class MyObject < ActiveFedora::Base
  ## This overrides the default behavior, which is to ask Fedora for an id
  # @see ActiveFedora::Persistence.assign_id
  def assign_id
    service.mint
  end

  private

  def service
    @service ||= Noid::Rails::Service.new
  end
end

Identifier/URI translation

As Noid::Rails overrides the default identifier minting strategy in ActiveFedora, you will need to let ActiveFedora know how to translate identifiers into URIs and vice versa so that identifiers are laid out in a sustainable way in Fedora. Add the following to e.g. config/initializers/active_fedora.rb:

baseparts = 2 + [(Noid::Rails::Config.template.gsub(/\.[rsz]/, '').length.to_f / 2).ceil, 4].min
ActiveFedora::Base.translate_uri_to_id = lambda do |uri|
                                           uri.to_s.sub(baseurl, '').split('/', baseparts).last
                                         end
ActiveFedora::Base.translate_id_to_uri = lambda do |id|
                                           "#{baseurl}/#{Noid::Rails.treeify(id)}"
                                         end

This will make sure your objects have Noid-like identifiers (e.g. bb22bb22b) that map to URIs in Fedora (e.g. bb/22/bb/22/bb22bb22b).

Overriding default behavior

The default minter in Noid::Rails is the file-backed minter to preserve default behavior.

To better support multi-host production installations that expect a shared database but not necessarily a shared filesystem (e.g., between load-balanced Rails applications), we highly recommend swapping in the database-backed minter.

Use database-based minter state

The database-based minter stores minter state information in your application's relational database. To use it, you'll first need to run the install generator:

$ rails generate noid:rails:install

This will create the necessary database migrations.

Then run rake db:migrate

To start minting identifiers with the new minter, override the AF::Noid configuration in e.g. config/initializers/noid-rails.rb:

require 'noid-rails'

Noid::Rails.configure do |config|
  config.minter_class = Noid::Rails::Minter::Db
end

Using the database-backed minter can cause problems with your test suite, where it is often sensible to wipe out database rows between tests (which destroys the database-backed minter's state, which renders it unusable). To deal with this and still get the benefits of using the database-backed minter in development and production environments, you'll also want to add the following helper to your spec/spec_helper.rb:

require 'noid/rails/rspec'

RSpec.configure do |config|
  include Noid::Rails::RSpec

  config.before(:suite) { disable_production_minter! }
  config.after(:suite)  { enable_production_minter! }
end

If you switch to the new database-backed minter and want to include in that minter the state of your current file-backed minter, Noid::Rails 2.x provides a new rake task that will copy your minter's state from the filesystem to the database:

# For migrating minter state from a file to a database
$ rake noid:rails:migrate:file_to_database
# For migrating minter state from a database to a file
$ rake noid:rails:migrate:database_to_file

Identifier template

To override the default identifier pattern -- a nine-character string consisting of two alphanumeric digits, two numeric digits, two alphanumeric digits, two numeric digits, and a check digit -- put the following code in e.g. config/initializers/noid-rails.rb:

require 'noid-rails'

Noid::Rails.configure do |config|
  config.template = '.ddddd'
end

For more information about the format of Noid patterns, see pages 8-10 of the Noid documentation.

Custom minters

If you don't want your minter's state to be persisted, you may also write and configure your own minter. First write up a minter class that looks like the following:

class MyMinter < Noid::Rails::Minter::Base
  def valid?(identifier)
    # return true/false if you care about ids conforming to templates
  end

  def read
    # return current minter state
  end

  def write!(state)
    # write a passed-in minter state
  end

  protected

  def next_id
    # return the next identifier from the minter
  end
end

Then add your new minter class to the Noid::Rails configuration (config/initializers/noid-rails.rb):

require 'noid-rails'

Noid::Rails.configure do |config|
  config.minter_class = MyMinter
end

And the service will delegate minting and validating to an instance of your customized minter class.

Contributing

If you're working on PR for this project, create a feature branch off of main.

This repository follows the Samvera Community Code of Conduct and language recommendations. Please do not create a branch called master for this repository or as part of your pull request; the branch will either need to be removed or renamed before it can be considered for inclusion in the code base and history of this repository.

Releasing

1. bundle install
2. Increase the version number in lib/noid/rails/version.rb
3. Increase the same version number in .github_changelog_generator
4. Update CHANGELOG.md by running this command:

github_changelog_generator --user samvera --project noid-rails --token YOUR_GITHUB_TOKEN_HERE

5. Commit these changes to the main branch

6. Run rake release

Help

The Samvera community is here to help. Please see our support guide.

Acknowledgments

This software has been developed by and is brought to you by the Samvera community. Learn more at the Samvera website.