Question

I have a subscription application with Users, Orders and DeliverySchedules (and other models that make a has_many :through necessary instead of a has_many).

class User < ActiveRecord::Base
    has_many :orders
    has_many :deliveryschedules, :through => :orders

class Deliveryschedule < ActiveRecord::Base
    has_many :orders
    has_many :users, :through => :orders

class Order < ActiveRecord::Base
    belongs_to :user
    belongs_to :deliveryschedule

My question is, why does

@allusers.each do |t|
    User.find_by_id(t.id).deliveryschedules.last.delivery_date
end

return something different from

@allusers.each do |t|
    t.deliveryschedules.last.delivery_date
end

My app is working, but I feel like I’m missing something fundamental here I can’t track down in the docs.

Answer 1

This is normal database behavior. The order of records that are returned from the database is undetermined, unless you specifically use ORDER BY. So it is possible that two different queries will return the rows in different order.