From STI, MTI or CTI, which is the current Rails 4 solution?

Question

I have a base events table and you want to have sub-tables for each type of event ( hiking , party , riverrun , etc.).

I see a lot of old (2011/2012) posts about CTI, MTI and STI. Some solutions worked in Heroku, while others did not.

What is the “current” Rails way of doing this type of thing? Was this added in Rails 4.x? Is there a magic stone that can handle this (using Postgres on Heroku)?

Some information if this helps:

In the future, there will be between 20-50 events, and each subcategory may consist of 80 columns. The site is hosted on Heroku. Running Rails 4.0.2

Answer 1

STI - Inheriting from individual tables is what you are looking for. http://api.rubyonrails.org/classes/ActiveRecord/Base.html#class-ActiveRecord::Base-label-Single+table+inheritance http://api.rubyonrails.org/classes/ActiveRecord/Inheritance.html

You create your model as always, but you add the even_type attribute as a string to your database. (default ist "type") You let EventModel know that it will be an inheritance column.

 class Event < ActiveRecord::Base self.inheritance_column = :event_type # dont forget your scopes to easy access them by type # Event.party or Event.ultrafestival scope :party, -> { where(event_type: 'Party') } scope :ultrafestival, -> { where(event_type: 'UltraFestival') } scope :tomorrowland, -> { where(event_type: 'TomorrowLand') } def host raise "needs to be implemented in your sub-class!" end end 

Than you will create some subclasses. Make sure they inherit from Event

 class Party < Event end class UltraFestival < Event end class Tomorrowland < Event end 

In principle, all objects are events! Therefore, if you go to Event.all , you will get them all! Technically, an object may be something else. All these "Events" will be stored in one table, they will differ by event_type , which in this example will be "party", "ultra_festival" or "budland".

Now you can add some special materials for each of these classes, for example

  class Party < Event def host "private homeparty PTY" end def publish_photostream end def call_a_cleaning_woman end end class UltraFestival < Event attr_accessor :location def host "UMF Festival Corp." end def is_in_europe? end def is_in_asia? end end class Tomorrowland < Event def host "ID&T" end def download_after_movie! end end 

This is the standard Rails path - over the years. Of course, it works on every hoster and with postgres.

// change: if your sub-events need some special tables in the database, then you need to go to MTI, multi-table-inheritance.