I have got this model: class User < ActiveRecord::Base has_and_belongs_to_many :roles before_destroy do |u|

Question

0

Asked: May 24, 20262026-05-24T16:13:31+00:00 2026-05-24T16:13:31+00:00

I have got this model: class User < ActiveRecord::Base has_and_belongs_to_many :roles before_destroy do |u|

0

I have got this model:

class User < ActiveRecord::Base
  has_and_belongs_to_many :roles

  before_destroy do |u|
    if u.superadmin? and User.joins(:roles).where(:roles => {:superadmin => true}).count == 1
      u.errors.add(:base, "cannot delete last admin user")
      return false
    end
    return true
  end
end

class Role < ActiveRecord::Base
  has_and_belongs_to_many :users
end

When I try to delete last superadmin, the before_destroy callback adds to errors array and return false. I get the error message in the controller, everything seems to be fine.

Except Rails3 deletes me record from the join table. Why? I returned false, as I return false it should not proceed with the deletion. Here is the log:

SQL (0.2ms)  SELECT COUNT(*) FROM "users" INNER JOIN "roles_users" ON "roles_users"."user_id" = "users"."id" INNER JOIN "roles" ON "roles"."id" = "roles_users"."role_id" WHERE "roles"."superadmin" = 't'
AREL (0.4ms)  DELETE FROM "roles_users" WHERE "roles_users"."user_id" = 1 AND "roles_users"."role_id" IN (1, 4)
Organization Load (0.4ms)  SELECT * FROM "organizations" INNER JOIN "organizations_users" ON "organizations".id = "organizations_users".organization_id WHERE ("organizations_users".user_id = 1 )

Thanks for help.