On Thu, Jul 16, 2009 at 9:27 AM, Joshua Russo<josh.r.ru...@gmail.com> wrote: > What are some examples of mutating operations (and other operations > for that matter) that you use in your models?
the most obvious are: - 'calculated' fields. the first example is the __unicode__() method, but lots others, like multiplying widht/height fields to get an 'area' field, (en/de)coding JSON data in one field to/from a python object, fetching a filesize from the filesystem, things like that. - 'pre-made filters'. like alex's example - overriding the save() method, to add some consistency checks, update other tables (like maintaining denormalized fields), override one field with another, etc. - other kinds of objects that could present a nicer API than just a bunch of DB records and tables, for example a tag soup, even if it's an extra table, it's presented as extra fields and operations on the 'tagged' model. - anything that Java developers could call the 'business layer', or anything that a DB manager would like to put into an stored procedure (unless you're able to actually do that!) a worthwhile goal is to make view functions really really thin. maybe just a few lines before calling the template or a generic view. if your model layer presents an API that is close to the concepts the user manages, but at the same time isn't tied to the specific web interface, you'll be able to easily rework the whole appearance of your website, quite possibly even change the whole user experience without rewriting the 'operational' code. -- Javier --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-users@googlegroups.com To unsubscribe from this group, send email to django-users+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/django-users?hl=en -~----------~----~----~----~------~----~------~--~---
