查询了大神的经验贴
http://stackoverflow.com/questions/19078044/disable-activerecord-for-rails-4
http://stackoverflow.com/questions/821251/how-to-configure-ruby-on-rails-with-no-database
其中点赞最多的也是我用的方法
If you are creating a new application, you can use -O to skip ActiveRecord: rails new my_app -O For existing applications: 1. Remove database adapter gems from your Gemfile (mysql2, sqlite3, etc.) 2. Change your config/application.rb Remove require ‘rails/all line and require frameworks you want to use, for example: require "action_controller/railtie" require "action_mailer/railtie" require "sprockets/railtie" require "rails/test_unit/railtie" 3. Delete your config/database.yml file, db/schema.rb and migrations (if any) 4. Delete migration check in test/test_helper.rb 5. Delete any ActiveRecord configuration from your config/environments files (this is what is causing your error)
这一步直接删除environments里所有的文件 This is all you need to do for an empty Rails app. If you run into problems caused by your existing code, stack trace should give you sufficient information on what you need to change. You might for example have some ActiveRecord configuration in your initializers.
6.删除controller里对Model的调用，把model里对ActiveRecord的依赖也删除
原文：http://www.cnblogs.com/iwangzheng/p/4820298.html