I was thinking that one generic approach to handle cross model validations could be:
[1] VALIDATE AT OBJECT LEVEL: Validate your specific cross model rules at the Rails object level (i.e. before a "save" using the Rails validate) - have a "model objects array" to add each associated model object that was part of the validation [2] ENSURE ALL MODELS THAT WERE PART OF VALIDATION ARE SAVED: In each models "after_save" then check it's list of "model objects array" to ensure each is actually saved, then if not either save all, or if there is an issue then issue manual Rollback so that all items are rolled back. Probem: I'm noting that re [1] and validating at the object level, if I allocate a book to a chapter, whilst the "chapter.book" works, the call "book_object.chapters" does not work??? Any way around this or is this a rails thing? i.e. my concept was in the object world the links should have been in place. Example: b = Book.new c = Chapter.new c.book = b c.book ==> works and gives b object b.chapters ==> DOES NOT WORK - gives [] tks On Tue, Jan 13, 2009 at 11:11 PM, Andrew Timberlake < [email protected]> wrote: > Greg > > On Tue, Jan 13, 2009 at 2:24 PM, Greg Hauptmann < > [email protected]> wrote: > >> thanks for pondering this one with me Andrew - I'll need to think about >> this tomorrow :) , couple of off-the-cuff comments: >> * very neat >> > > Thank you > > >> >> * just wondering if this will work for multiple magazines linked to one >> article (i.e. many-to-many) >> > > It does but I only focussed on the magazine side as with the > magazine/article relationship it's more likely that you'll create a magazine > and add articles than create an article and add magazines. > You can do it though, you'll just need to implement an add_magazine method > to the article model > The validations definitely work both ways, check the tests. > > >> >> * do you think there's no way to solve this without creating a new method >> in fact (like your "add_article")? >> > > I played around with the various collection methods but each of them tries > to save a model at some point where the other isn't saved and then the > validations will fail. Also most of the association methods rely on there > being an id in the association model (i.e. it must be saved). > My solution doesn't require either model to be saved and handles the saving > of children when needed. > My solution will also continue to work after creation if you're updating > deleting children etc. E.g. You don't have to use the add_article method > once you have at least one article saved with a link to the magazine. > You could do: > magazine.add_article article > magazine.save! > magazine.articles << Article.new(...) > > >> * one thing that this has made me realize is that I was also thinking >> of/assuming that my validation checks would be database based (e.g. search >> database to see result), but by working in the object world this helps >> remove the inherit database transaction/commits only approach where I was >> getting stuck seeing how to do it >> > > You could deal with it more in the database but then you would lose the > abstraction of the models and you would need to couple more tightly to the > database. > > >> regards >> Greg >> > > > -- > Andrew Timberlake > http://ramblingsonrails.com > http://www.linkedin.com/in/andrewtimberlake > > "I have never let my schooling interfere with my education" - Mark Twain > > > > -- Greg http://blog.gregnet.org/ --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
