Better way to build has_one association or update if it exists

Question

My discount class has a sales_period. I want to write a method which can build this association when it does not exist, or updates it when it does exist. Currently I am writing the following if condition.

class Discount < ActiveRecord::Base
  has_one :sales_period

  def fetch_period
    end_date = ...
    if sales_period.nil?
      build_sales_period( end: end_date )
    else
      sales_period.end = end_date
    end
  end
end

Is there a better way to do this, similar to find_or_create?

Answer 1

Not quite what you're looking for but you can shorten it slightly.

def fetch_period
  end_date = ...
  period = sales_period || build_sales_period
  period.end = end_date
end

Answer 2

find_or_initialize is similar to first_or_initialize. Ex:

def fetch_period
  end_date = ...
  sales_period.find_or_initialize_by_end(end_date)
end

Also, I'd rename end, it's a ruby keyword. You'll probably get some weird bug when something tries to eval the code or some such, and it'll be super confusing.