On Tue, Jan 3, 2012 at 11:14 PM, Linus Pettersson < [email protected]> wrote:
> Hi! > > I have an app with products, categories, subcategories and > resellercategories. > > Products.... > > belongs_to :resellercategory > has_one :subcategory, :through => :resellercategory > has_one :category, :through => :subcategory > > So, there are a lot of resellercategories that are (manually) mapped to my > fewer subcategories. > > I have a before_save in my products model that sets if the product is > complete: > > def check_complete > self.complete = !image_small.blank? && !subcategory.blank? > nil > end > > So, if the resellercategory that the product is related to is mapped to a > subcategory, the product is marked as "complete". However, at the moment it > is only updated when the product is saved, I also want it to be updated > when the resellercategory is mapped to a subcategory. > > Is there any good way to do this? Should I create an after_save in my > resellercategory that iterates through all the products and re-saves all of > them to get the field updated? > Any easier/more effective way? > I am not sure I follow exactly, but ... Answer 1: I assume this " ... when the resellercategory is mapped to a subcategory ..." creates (or modifies) a ResellerCategory object (and saves it later to the database)? So as you suggest: "... Should I create an after_save in my resellercategory that ..." updates all associated products. Instead of "... iterates through all the products and re-saves all of them to get the field updated? ..." you could use an update_all , but that seems quite low-level database hacking (no models instantiated, no before/after filters ...). http://apidock.com/rails/ActiveRecord/Relation/update_all #untested code !! Product.where(:reseller_category_id => reseller_category.id).update_all(:complete => true) This does not feel comfortable, but it would probably work ... Answer 2: In reality, the Product.complete column is a de-facto cache for information that is already present in the database. Unless your have real performance problems associated with it, I would try to make a scope class Product < ActiveRecord::Base scope :complete ... that limits the products to those that are complete (that is, they have a category and a small_image). Then Product.complete.where. ... will inlcude the correct SQL to only select the complete products, _without_ the implicit caching problem that you are facing now. Very true: > There are only two hard things in Computer Science: cache > invalidation and naming things. > > Phil Karlton HTH, Peter -- Peter Vandenabeele http://twitter.com/peter_v http://rails.vandenabeele.com -- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en.
