Is there a legitimate use case where a system may contain multiple database? What if you have many applications but want a centralized user database that is accessible to your numerous apps that also have a hefty database schema of its own? Here's a possible solution that is very easy to implement, what do you think? 1. Add new database connecti…

database.example.yml

#Add multiple databases to a Rails App
#given you have other database connections you'd like to define inside the rails app
#Here's a possible solution to define multiple databases
#do not copy this template over your current configuration 
#just add/name the connection and add _staging or _production (whichever environment the DB is for)
#to the current database.yml

#imagine we have a seperate database that manages members
#these members have access to this app, and 10 other apps you / your start-up ;) has developed.
#so the members database is separate and here we make members accessible to this app.
#once this is added you can create a Class with this established connection.

members_development:
 adapter: 
 encoding: 
 reconnect: 
 database: 
 pool: 
 username: 
 password: 
 host: 
 port: 
 socket:

members_production:
 adapter: 
 encoding:
 reconnect: 
 database: 
 pool: 
 username: 
 password: 
 host: 
 port:
 socket: 

#below are default db settings for the app, you can put the external databases above or below.
#I'd put it at the bottom of the yaml, but for this example I put it up top so you could see it first.

development:
 adapter: 
 encoding: 
 pool: 
 database: 
 username: 
 password: 
 host: 
 port: 

test:
  adapter: 
  encoding: 
  reconnect: 
  database: 
  pool: 
  username: 
  password: 
  host: 
  socket: 

production:
 adapter: 
 encoding: 
 pool: 
 database: 
 username: 
 password: 
 host: 
 port: 



  

member.rb

class Member < ActiveRecord::Base
  
  establish_connection "members_#{Rails.env}"
    
    #now that you are connected you can add associations
    #your database is seperate because "members" database manages about "10 other" apps with thier own database
    #nonetheless, rails internally does the data mapping inside the application itself and we just need
    #to update our routes.rb to nest these resources
    has_many :post, dependent: :destroy
    has_many :comment, dependent: :destroys
    
end

routes.example.rb

#for mapping and active relations update your routes
#so the rails app can know the relationships between the 
#different tables even when in a different database

thenextbigthing::Application.routes.draw do
  
  resources :members do
    resources :posts do
      resources :comments
    end
  end

end