Dynamically add includes to an association?

I have an association user.lessons. Sometimes i just want the lessons,
other times i want the lessons to eager-load one of their own
associations, 'assets'. Theres a couple of ways i can see to deal with
this and i'm not super happy with any of them.

approach 1) Make two associations:
has_many :lessons
has_many :lessons_with_assets, :class_name => "Lesson", :include =>
[:assets]

#then, if i want the assets, call
@user.lessons_with_assets

This is actually my favorite but it still feels a bit clumsy

approach 2) Don't use the association if i want to eager load
#just do a regular find
Lesson.find_all_by_user_id(@user.id, :include => [:assets])

Is there another way? This example is simple but i have other
associations that go through join tables and are polymorphic (eg using
the has_favorite plugin) that are a bit more arsey to use.

thanks
max

Max

There’s another way, named_scopes.

in the Lesson model, add
named_scope :with_assets, :include => :assets

then you can call
lessons
or
lessons.with_assets

aha...so, if i have lots of different associations (in user and other
classes) that return a collection of lessons i can just add
".with_assets" to the end? eg

user.usb_lessons.with_assets

user.lessons.with_assets

resource.recent_lessons.with_assets

etc
?

Max

There's another way, named_scopes.

in the Lesson model, add
named_scope :with_assets, :include => :assets

then you can call
lessons
or
lessons.with_assets

See also http://ryandaigle.com/articles/2008/8/20/named-scope-it-s-not-just-for-conditions-ya-know

Fred

Yes, on more complicated joins, where Rails thinks it will be better, it does split the query into multiple queries.