Replace CollectionProxy#load_target in PaperTrail::Model#record_destroy with CollectionProxy#reset

[sedx]

With this line, when object destroyed and version was created PaperTrail load associated version. It's bring useless query to DB.

From log:

Started DELETE "/deploys/48" for 127.0.0.1 at 2016-05-18 12:29:33 +0500
User Load (0.5ms) SELECT users.* FROM users WHERE users.active = 1 AND users.deleted_at IS NULL AND users.id = 1 ORDER BY users.id ASC LIMIT 1
Processing by DeploysController#destroy as HTML
...
SQL (0.4ms) UPDATE deploys SET deploys.deleted_at = '2016-05-18 07:29:33' WHERE deploys.id = 48
SQL (0.4ms) INSERT INTO user_actions (item_id, item_type, event, object, whodunnit, created_at) VALUES (48, 'Deploy', 'destroy', 'OBJECT_INFO', '1', '2016-05-18 07:29:33')
#useless request to DB
UserAction Load (0.6ms) SELECT user_actions.* FROM user_actions WHERE user_actions.item_id = 48 AND user_actions.item_type = 'Deploy' ORDER BY created_at DESC, user_actions.created_at ASC, user_actions.id ASC
(87.9ms) COMMIT
Redirected to http://server.dev/deploys
Completed 302 Found in 113ms (ActiveRecord: 89.9ms)

user_actions is a custom version class:

class Deploy < ActiveRecord::Base
  has_paper_trail class_name: "UserAction",
                  versions: :user_actions,
                  version: :user_action,
                  unless: Proc.new{ PaperTrail.whodunnit.blank? },
                  skip: ( base::UNTRACKED_ATTRIBUTES || [] ) + ALWAYS_UNTRACKED
end

module PaperTrail
  class Version < ActiveRecord::Base
    PaperTrail::Rails::Engine.eager_load!
      include PaperTrail::VersionConcern
      self.abstract_class = true
  end
end

class UserAction < PaperTrail::Version
  belongs_to :user, ->{unscope(:where)}, foreign_key: :whodunnit
  default_scope ->{order('created_at DESC')}
  self.table_name = :user_actions
end

I'm not sure that my solution is correct, because I don't actually know why need to call#load_target, but tests was not broken.

There are bug_report file, if interested.

[jaredbeck]

I'm not sure that my solution is correct, because I don't actually know why need to call#load_target, but tests was not broken.

By using git blame, I was able to find this discussion of load_target: #144, which I'm still reading.

[jaredbeck]

Instead of removing this line, how about using CollectionProxy#reset? That way, we know the association will not be cached.

[sedx]

@jaredbeck Thanks for advice! I'm don't know about CollectionProxy#reset. Replace CollectionProxy#load_target with CollectionProxy#reset. Also update tests for more simple detect N+1 query in assotiation's tests

[jaredbeck]

Thanks, Ilya! Merged offline in 0eba14d, without bullet.

I was unsure about introducing bullet. Let's discuss it in a separate PR.