Oracle + join model, primary key issue

I'm using

ActiveRecord::Base.primary_key_prefix_type = :table_name_with_underscore

in my current project.

My problem is that this setting seems to be causing me some issues with my join model's primary keys.

For example I have these three models:

class User < ActiveRecord::Base has_many :user_ugroups has_many :ugroups, :through => :user_ugroups end

class Ugroup < ActiveRecord::Base has_many :user_ugroups has_many :users, :through => :user_ugroups end

class UserUgroup < ActiveRecord::Base belongs_to :user belongs_to :ugroup end

My migration for the join table looks like this:

def self.up create_table :user_ugroups, :primary_key => :user_ugroups_id do |t| t.integer :user_id, :null => false t.integer :ugroup_id, :null => false end end

So when I create a UserUgroup like so:

UserUgroup.create!( :user => @gdonald, :ugroup => @admin )

ActiveRecord tries to insert a NULL for the user_ugroups_id field and then I get this:

ActiveRecord::StatementInvalid: OCIError: ORA-01400: cannot insert NULL into ("MYPROJDB"."USER_UGROUPS"."USER_UGROUPS_ID"): INSERT INTO user_ugroups (user_ugroups_id, user_id, ugroup_id) VALUES(NULL, 1, 1)

The migration creates my USER_UGROUPS_SEQ without issue, but then it doesn't get used.

I found a work-around for the issue:

before_create :get_id

def get_id self.ugroup_permission_id = connection.next_sequence_value( self.class.sequence_name ) end