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Real PG enums for ActiveRecord
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README.md

Activerecord::RealEnums

Supporting enumerations in Rails has up to now always been done on the application layer.

The symbolize gem allows storing a limited set of different string values to a field. On a database level it is still possible to store abritrary strings.

Rails 4.1 introduced enums which fulfils the same purpose but stores the different types as integers. The mapping, validation is also handled on the application layer. And even worse in order to query for a specific enum it is necessary to lookup the according values for each query:

Conversation.where(status: Conversation.statuses[:archived])

This gem takes advantage of the PostgreSQL enum type that will handle all the validations:

Conversation.where(status: :archived)

Installation

Add this line to your application's Gemfile:

gem 'activerecord-real_enums'

And then execute:

$ bundle

Or install it yourself as:

$ gem install activerecord-real_enums

Usage

Migrations

To be able to use PostgreSQL enums, I suggest to create the according type in a separate migration:

class CreateConversationStatusEnum < ActiveRecord::Migration
  def up
    execute "CREATE TYPE conversation_status AS ENUM ("active", "archived");"
  end

  def down
    execute "DROP TYPE conversation_status;"
  end
end

from then on, the type conversation_status can be used as a regular type:

class AddColumnsToTeam < ActiveRecord::Migration
  def change
    add_column :conversations, :status, :conversation_status
  end
end

Model

To reference the type correctly (e.g. for queries) the enum needs to be added to the model:

class Converation < ActiveRecord::Base
  real_enum :status, type: :conversation_status
end

real_enums will add the necessary validations in the background.

From then on, it is possible to query all conversations by status:

Conversation.where(status: :archived) # strings and symbols, both work

Caveats

This is a first draft. Completely usable but not feature complete:

  • no posibility to query all available values for enum
  • currently only support for PostgreSQL (although MySQL also has an enum type)
  • no helper methods for migration (AFAIK not officically supported to write own migration methods (that are reversible))

Contributing

  1. Fork it ( https://github.com/[my-github-username]/activerecord-real_enums/fork )
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create a new Pull Request
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