Question
Here my models:
class User < ActiveRecord::Base
has_many :bookmarks
end
class Topic < ActiveRecord::Base
has_many :bookmarks
end
class Bookmark < ActiveRecord::Base
belongs_to :user
belongs_to :topic
attr_accessible :position
validates_uniqueness_of :user_id, :scope => :topic_id
end
I want to fetch all topics
with, for current_user
, the associated
bookmark
. ATM, I do:
Topic.all.each do |t|
bookmark = t.bookmarks.where(user_id: current_user.id).last
puts bookmark.position if bookmark
puts t.name
end
This is ugly and do too much DB queries. I would like something like this:
class Topic < ActiveRecord::Base
has_one :bookmark, :conditions => lambda {|u| "bookmarks.user_id = #{u.id}"}
end
Topic.includes(:bookmark, current_user).all.each do |t| # this must also includes topics without bookmark
puts t.bookmark.position if t.bookmark
puts t.name
end
Is this possible? Have I any alternative?
Thank you!
Answer
*Hmm I'm not sure I understood your question but this may help you:
# code
class Topic < ActiveRecord::Base
scope :for_user, lambda { |user| includes(:bookmarks).where(bookmarks: { user_id: user.try(:id) || user} ) }
# call
Topic.for_user(current_user) # => Array of Topics
As you can see the parameter of the scope for_user
can be a User
object OR a user id.
Hope this helps!
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