override active_record.initialize_database in rails (rails4)

application.rb

require File.expand_path('../boot', __FILE__)

require 'rails/all'

if ar_initdb = ActiveRecord::Railtie.initializers.find {|item| item.name == 'active_record.initialize_database'}
  ActiveRecord::Railtie.initializers.delete(ar_initdb)
  
  ActiveRecord::Railtie.initializer :after => ar_initdb.after do
    ActiveSupport.on_load(:active_record) do
      self.configurations = Rails.application.config.database_configuration

      begin
        establish_connection
      rescue ActiveRecord::NoDatabaseError, ActiveRecord::AdapterNotSpecified, ActiveRecord::AdapterNotFound
        if app.config.database_not_required
          app.config.middleware.delete "ActiveRecord::QueryCache"
          app.config.middleware.delete "ActiveRecord::ConnectionAdapters::ConnectionManagement"
        else
          warn <<-end_warning
Oops - You have a database configured, but it doesn't exist yet!

Here's how to get started:

1. Configure your database in config/database.yml.
2. Run `bin/rake db:create` to create the database.
3. Run `bin/rake db:setup` to load your database schema.
end_warning
          raise
        end
      end
    end
  end
end

# Rest of your application.rb file