```ruby
class Shipment < ActiveRecord::Base
  belongs_to :pod
  belongs_to :user

  def crops
    pod.instructions.map{|x| x.ship ? x.crop : nil}.compact
  end
  
  def ship!
    self.shipped = true
    save!
    # Tell the user!
    Notifications.shipped(self.user).deliver
  end
  
end
```

Send shipping email whenever shipped flag is set to true
user
```ruby
class Shipment < ActiveRecord::Base
  belongs_to :pod
  belongs_to :user

  after_save :send_shipment_email

  def crops
    pod.instructions.map{|x| x.ship ? x.crop : nil}.compact
  end
  
  def ship!
    update_attributes!(shipped: true)
  end

  def send_shipment_email
    if shipped_changed? && shipped_was == false && shipped == true
      # Tell the user!
      Notifications.shipped(self.user).deliver      
    end
  end

  
end
```
assistant