README
NestedHasManyThrough
====================
This plugin makes it possible to define has_many :through relationships that
go through other has_many :through relationships, possibly through an
arbitrarily deep hierarchy. This allows associations across any number of
tables to be constructed, without having to resort to find_by_sql (which isn't
a suitable solution if you need to do eager loading through :include as well).
It is hoped that this feature will in time be applied to the Rails core, after
which this plugin will become unnecessary.
See: http://dev.rubyonrails.org/ticket/6461
Example
-------
class Pub < ActiveRecord::Base
belongs_to :city
end
class City < ActiveRecord::Base
belongs_to :country
has_many :pubs
end
class Country < ActiveRecord::Base
belongs_to :planet
has_many :cities
has_many :pubs, :through => cities
end
class Planet < ActiveRecord::Base
belongs_to :star_system
has_many :countries
has_many :cities, :through => :countries
# Now we go through a has_many :through association -
# something that wasn't previously possible
has_many :pubs, :through => :cities
end
class StarSystem < ActiveRecord::Base
has_many :planets
has_many :countries, :through => :planets
# We can also use a has_many :through association for the source
# association; in this case, Country#pubs
has_many :pubs, :through => countries
end