Question

On Amazon’s EC2 using Ubuntu, when I execute rake db:migrate as:

bundle exec rake db:migrate RAILS_ENV="production" --trace

I get the error ActiveRecord::ConnectionNotEstablished as shown below

 ** Invoke db:migrate (first_time)
 ** Invoke environment (first_time)
 ** Execute environment
 ** Execute db:migrate
 rake aborted!
 ActiveRecord::ConnectionNotEstablished
 /usr/local/rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.0.3/lib/active_record/connection_adapters/abstract/connection_pool.rb:316:in `retrieve_connection'

I can login to mysql with the username and password in my config/database.yml file
and the database is there. So mysql is running, and that is not the problem.

My config/database.yml file looks like:

 production:
   adapter: mysql2
   encoding: utf8
   reconnect: false
   database: app_production
   pool: 5
   username: root
   password: password
   host: localhost
   socket: /run/mysqld/mysqld.sock

Here are my gems from gem list:

 abstract (1.0.0)
 actionmailer (3.0.3)
 actionpack (3.0.3)
 activemodel (3.0.3)
 activerecord (3.0.3)
 activeresource (3.0.3)
 activesupport (3.0.3)
 arel (2.0.10)
 builder (2.1.2)
 bundler (1.0.10 ruby)
 cgi_multipart_eof_fix (2.5.0)
 daemons (1.0.10)
 erubis (2.6.6)
 eventmachine (0.12.10)
 fastthread (1.0.7)
 gem_plugin (0.2.3)
 i18n (0.6.0)
 mail (2.2.19)
 mime-types (1.17.2)
 mongrel (1.2.0.pre2)
 mysql2 (0.2.7)
 polyglot (0.3.3)
 rack (1.2.5)
 rack-mount (0.6.14)
 rack-test (0.5.7)
 rails (3.0.3)
 railties (3.0.3)
 rake (0.9.2.2)
 rmagick (2.13.1)
 thin (1.2.7)
 thor (0.14.6)
 treetop (1.4.10)
 tzinfo (0.3.31)
 xmpp4r (0.5)

The error in connection_pool.rb is happening at the same place as described in this post whose answer says that a connection needs to be established on ActiveRecord::Base. The code is failing in connection_pool.rb because it is getting sent klass = ActiveRecord::Base which doesn’t have a connection. So I tried creating a model my_connection_base.rb that looks like the following

 require 'active_record'

 class MyConnectionBase < ActiveRecord::Base

      MyConnectionBase.establish_connection(
        :adapter => "mysql2",
        :host => "localhost",
        :username => "<your database username>",
        :password => "<your database password>",
        :database => File.dirname(__FILE__) + "app_production"
      )
   self.abstract_class = true
 end

And then all of my models inherit MyConnectionBase as in role.rb below:

require 'my_connection_base'

class Role < MyConnectionBase
  has_and_belongs_to_many :users
end

But I still get ActiveRecord::ConnectionNotEstablished when I try to run a migration. Is there something else I need to do with Rails 3 to ensure that the connection is made to mysql before performing the migration?

Answer 1

I was able to get the migrations to work by adding db:create to the rake command line as shown below:

 bundle exec rake db:create db:migrate RAILS_ENV="production" 

I don’t know why db:create is needed now. One thing I didn’t mention is that these migrations were transferred from a Rails 2 application to a Rails 3 application. I’m still having trouble creating pages in the migration, as shown below in the Page.create section that I commented out:

20101014205123_create_pages.rb

 class CreatePages < ActiveRecord::Migration
   def self.up
     create_table :pages do |t|
       t.column :title, :string
       t.column :permalink, :string
       t.column :body, :text
       t.column :created_at, :datetime
       t.column :updated_at, :datetime
       t.timestamps
     end

 #   Page.create(:title => "Home",
 #               :permalink => "welcome-page",
 #               :body => "Welcome to Home")

   end

   def self.down
     drop_table :pages
   end
 end

It also looks like the initial data creation can be done in db/seeds.rb which is where I transfered the Page.create code. I am still trying to get that to work using:

 bundle exec rake db:create db:seed RAILS_ENV="production" --trace

and I’m getting the error:

 uninitialized constant Page

I was able to fix this error by requiring the model in db/seeds.rb as shown below:

require File.expand_path('../../app/models/page', __FILE__)

Page.create(:title => "Home",
            :permalink => "welcome-page",
            :body => "Welcome to Home")