How do I remove ActiveRecord from an existing Rails 4 Application?

Question

I started off a Ruby on Rails Project which includes a simple recommender system with ActiveRecord and Neography. Now I found out about neo4j.rb, which is going to simplify my life by a lot. :-)

I learned by now, that I could create a new Application without ActiveRecord as follows:

rails new xyz -O

I could do that and copy paste most of my files / code into that new project. Or is there an easier way?

I am still thinking about if that step is even necessary. Is it possible to use both neo4j.rb and ActiveRecord in parallel? I am thinking of running the authentication system (e.g. Devise) with ActiveRecord and my recommender system in neo4j. Does anyone have experiences with such an approach?

Answer 1

Follow these steps

1. Remove database adapter gems from your Gemfile, e.g., mysql2, sqlite3, etc

2. From application.rb, remove require 'rails/all' and add

   require "action_controller/railtie"
   require "action_mailer/railtie"
   require "sprockets/railtie"
   require "rails/test_unit/railtie"
   

3. Delete database.yml, schema.rb and all the migrations

4. Delete migration checks from test/test_helper.rb
5. Delete all activerecord related configuration from config/environments

Hope this helps!

Source - Disable ActiveRecord for Rails 4

Answer 2

For those using the rails-api gem you may encounter a similar error when using the --skip-active-record flag when doing rails-api new my_api. The current fix (until a new corrected version of the gem is released) is to edit your rails-api gem to have this commit. Use bundle open and replace the old Gemfile with the new corrected one. Rerun and you should be all set.

Answer 3

For the second part of the question: I can recommend to use https://github.com/neo4jrb/devise-neo4j for the authentication system.