Trying to use multiple databases - getting ActiveRecord Connection Not Established

Question

I'm trying to set up ActiveRecord so I can use multiple database connections in my application. I am not using Rails.

To do this, I set up an abstract class for each of my databases:

  class BuoyDatabase < ActiveRecord::Base
    self.abstract_class = true
    establish_connection $database_config['buoy_database']
  end

Then I inherit from the OneDatabase class:

  class Buoy < BuoyDatabase
    has_many :buoyDatas, :foreign_key => 'buoy_id'
  end

  class BuoyData < BuoyDatabase
    belongs_to :buoy
  end

I can successfully create and read instances of both Buoy and BuoyData, but I can't get any related records:

Buoy.find_by_id(...).buoyDatas  # gives ActiveRecord::ConnectionNotEstablished

Details of the error:

ActiveRecord::ConnectionNotEstablished: ActiveRecord::ConnectionNotEstablished
from /Users/admin/.rvm/rubies/ruby-1.9.3-head/lib/ruby/gems/1.9.1/gems/activerecord-3.1.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:409:in `retrieve_connection'
from /Users/admin/.rvm/rubies/ruby-1.9.3-head/lib/ruby/gems/1.9.1/gems/activerecord-3.1.0/lib/active_record/connection_adapters/abstract/connection_specification.rb:107:in `retrieve_connection'
from /Users/admin/.rvm/rubies/ruby-1.9.3-head/lib/ruby/gems/1.9.1/gems/activerecord-3.1.0/lib/active_record/connection_adapters/abstract/connection_specification.rb:89:in `connection'
from /Users/admin/.rvm/rubies/ruby-1.9.3-head/lib/ruby/gems/1.9.1/gems/activerecord-3.1.0/lib/active_record/associations/alias_tracker.rb:69:in `connection'
from /Users/admin/.rvm/rubies/ruby-1.9.3-head/lib/ruby/gems/1.9.1/gems/activerecord-3.1.0/lib/active_record/associations/alias_tracker.rb:54:in `initial_count_for'
from /Users/admin/.rvm/rubies/ruby-1.9.3-head/lib/ruby/gems/1.9.1/gems/activerecord-3.1.0/lib/active_record/associations/alias_tracker.rb:12:in `block in initialize'
from /Users/admin/.rvm/rubies/ruby-1.9.3-head/lib/ruby/gems/1.9.1/gems/activerecord-3.1.0/lib/active_record/associations/alias_tracker.rb:29:in `yield'
from /Users/admin/.rvm/rubies/ruby-1.9.3-head/lib/ruby/gems/1.9.1/gems/activerecord-3.1.0/lib/active_record/associations/alias_tracker.rb:29:in `default'
from /Users/admin/.rvm/rubies/ruby-1.9.3-head/lib/ruby/gems/1.9.1/gems/activerecord-3.1.0/lib/active_record/associations/alias_tracker.rb:29:in `aliased_name_for'
from /Users/admin/.rvm/rubies/ruby-1.9.3-head/lib/ruby/gems/1.9.1/gems/activerecord-3.1.0/lib/active_record/associations/alias_tracker.rb:17:in `aliased_table_for'
from /Users/admin/.rvm/rubies/ruby-1.9.3-head/lib/ruby/gems/1.9.1/gems/activerecord-3.1.0/lib/active_record/associations/join_helper.rb:15:in `block in construct_tables'
from /Users/admin/.rvm/rubies/ruby-1.9.3-head/lib/ruby/gems/1.9.1/gems/activerecord-3.1.0/lib/active_record/associations/join_helper.rb:14:in `each'
from /Users/admin/.rvm/rubies/ruby-1.9.3-head/lib/ruby/gems/1.9.1/gems/activerecord-3.1.0/lib/active_record/associations/join_helper.rb:14:in `construct_tables'
from /Users/admin/.rvm/rubies/ruby-1.9.3-head/lib/ruby/gems/1.9.1/gems/activerecord-3.1.0/lib/active_record/associations/association_scope.rb:53:in `add_constraints'
from /Users/admin/.rvm/rubies/ruby-1.9.3-head/lib/ruby/gems/1.9.1/gems/activerecord-3.1.0/lib/active_record/associations/association_scope.rb:33:in `scope'
from /Users/admin/.rvm/rubies/ruby-1.9.3-head/lib/ruby/gems/1.9.1/gems/activerecord-3.1.0/lib/active_record/associations/association.rb:99:in `association_scope'
from /Users/admin/.rvm/rubies/ruby-1.9.3-head/lib/ruby/gems/1.9.1/gems/activerecord-3.1.0/lib/active_record/associations/association.rb:88:in `scoped'
from /Users/admin/.rvm/rubies/ruby-1.9.3-head/lib/ruby/gems/1.9.1/gems/activerecord-3.1.0/lib/active_record/associations/collection_association.rb:367:in `find_target'
from /Users/admin/.rvm/rubies/ruby-1.9.3-head/lib/ruby/gems/1.9.1/gems/activerecord-3.1.0/lib/active_record/associations/collection_association.rb:324:in `load_target'
from /Users/admin/.rvm/rubies/ruby-1.9.3-head/lib/ruby/gems/1.9.1/gems/activerecord-3.1.0/lib/active_record/associations/collection_proxy.rb:51:in `load_target'
from /Users/admin/.rvm/rubies/ruby-1.9.3-head/lib/ruby/gems/1.9.1/gems/activerecord-3.1.0/lib/active_record/associations/collection_proxy.rb:89:in `method_missing'

There is a work-around: see stackoverflow.com/questions/7390623/… — jasonkarns
– jasonkarns, Commented Nov 14, 2011 at 21:23
@jasonkarns - If you're game to recap the solution as your own answer, I'll delete my answer. (See meta.stackexchange.com/questions/90263/… for elaboration of why this is helpful.) Thanks! — DreadPirateShawn
– DreadPirateShawn, Commented Oct 10, 2013 at 6:33

Community · Accepted Answer · 2017-05-23 11:51:09Z

2

The workaround is to establish a connection on ActiveRecord::Base itself. It doesn't matter to which database the connection is made. This connection is only needed so that ActiveRecord can get the meta information necessary to handle associations and whatnot. You need not use the connection at all, once established.

This issue is a duplicate of ActiveRecord 3.1.0 multiple databases and the workaround is first described here: https://stackoverflow.com/a/7406374/29729

edited May 23, 2017 at 11:51

CommunityBot

11 silver badge

answered Oct 24, 2013 at 16:28

jasonkarns

1,8522 gold badges15 silver badges17 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Trying to use multiple databases - getting ActiveRecord Connection Not Established

1 Answer 1

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related