I'm fairly new to RoR and I think I don't get some of the ActiveRecord
magic.
I have:
# a lookup table (used to show countries in a <select>)
class Country < ActiveRecord::Base
has_many :breeders
validates_presence_of :name
end
# a table of companies (each located in a specific country).
class Breeder < ActiveRecord::Base
belongs_to :country
validates_presence_of :name
validates_associated :country # may be NIL when we don't know it yet
end
Currently, I do in the controller to create or update a Breeder:
What exactly is the difference for @breeder.country when it's assigned
a (found) Country or breeder.country_id is set by
Breeder.new(params[:breeder]) ?
Both save the country_id to the "breeders" table; besides that, the
Breeder "knows" that the country_id (may) refer to a country and could
do the find above itself.
What exactly is the difference for @breeder.country when it's assigned
a (found) Country or breeder.country_id is set by
Breeder.new(params[:breeder]) ?
There is no difference, except that your controller code gets
unneccessarily verbose.
The following should work just fine:
def create
@breeder = Breeder.new(params[:breeder])
if @breeder.save
Much simpler.
AR lazily initialises the breeder.country field on first access and
internally performs a Country.find(breeder.country_id). Conversely, if
you set the country field, country_id is updated.
In short, don't bother with finding and setting the country yourself.
