On 3 May 2012 15:49, Mauro <mrsan...@gmail.com> wrote: > On 3 May 2012 16:41, Jeremy Walker <jez.wal...@gmail.com> wrote: > > > > > > On 3 May 2012 15:28, Mauro <mrsan...@gmail.com> wrote: > >> > >> Hello. > >> I've read about examples on inheritance with rails. > >> Here is an example: > >> > >> > >> > http://juixe.com/techknow/index.php/2006/06/03/rails-single-table-inheritance/ > >> > >> The way is to add a type field in the table. > >> So if I have an Animal class with an attribute name, I can inherit > >> from this class like: > >> > >> Dog < Animal, Cat < Animal, and so on. > >> > >> With the type field in the table I can do Dog.all, Cat.all having > >> automaticaly all dogs, all cats, etc. > >> But what if I want to add some other attributes to Dog or Cat classes? > >> In the example above all classes have only name attribute. > >> What if I want inherit from Animal extending attributes and adding, > >> for example, an attribute like canFly? for inherited classes? > > > > > > Hi, > > > > You can add columns to the animals table that only some classes use. IMHO > > this is not a nice solution. > > > > I have written the SuperSTI gem that I think offers a nicer solution. > Read > > about it at > > http://www.ihid.co.uk/projects/super_sti and > https://github.com/ihid/super_sti > > > > Feel free to email me personally to discuss it further. > > It creates a table for every inherited class. > So in my example I must have a table animals, a table dogs and a table > cats. > It's the same if I create different models: Animal, Dog, Cat without > using inheritance.
No, it creates an animals table, and then creates extra linked tables for any extra attributes. So you'd create an animals table with all the shared attributes, then a dogs table that only has the extra attributes on there. So you don't have any duplication, and don't have a load of nullable columns on a super table. -- 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 rubyonrails-talk@googlegroups.com. To unsubscribe from this group, send email to rubyonrails-talk+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en.
