Is there a better way to do this find in ruby

Question

ok so i have this helper

def playlist_count(user, site_id)
  user.companies.local(site_id).map(&:playlists).flatten.count
end

which will return the playlist count for all the companies

class Playlist < ActiveRecord::Base
  belongs_to :company
  scope :active, where('end_date >= ? AND player_id IS NOT NULL', Date.today)

class Company < ActiveRecord::Base
  has_many :playlists, :dependent => :destroy
  scope :local, lambda{ |site_id| where(:site_id => site_id) }

the problem is it the helper is getting ugly and the other problem is that i need the active playlists (defined by my scope in the playlist model)

Is there a way to clean up my helper or use a scope instead to get the active playlist count for all the users companies

Answer 1

您可以反过来运行查询：

Playlist.active.where(:company_id => user.companies.local(site_id)).count

Answer 2

You can apply scopes to associations. Try this:

user.companies.local(site_id).map { |company| company.playlists.active.count }.sum

Another advantage is that it'll execute select count(*) ... SQL statement instead of fetching all active playlists from the DB and counting them in Ruby.

If you care about performance it'll be more efficient to join tables and count active playlists for all user's companies in a single SQL statement rather than iterating over companies and making count query for each one of them.