Thanks for the responses. There are a number of subclasses and I won't know the specifics initially. I'll check out the GenericForeighnKey. Sounds like it is what I want.
Thanks again, Peter On Sep 16, 8:34 am, Malcolm Tredinnick <[EMAIL PROTECTED]> wrote: > On Mon, 2008-09-15 at 18:10 -0700, Peter Bailey wrote: > > Hi all. I have a set of classes (web page items like radios, > > checkboxes, etc.) They are built on a superclass - Item. I need a > > join table to link them to specific pages in which I also store a > > position (PageItem) . Here is a snippet: > > > # > > --------------------------------------------------------------------------- > > ------- > > # will use this for subclassing into our item subtypes > > # > > --------------------------------------------------------------------------- > > ------- > > > class Item(models.Model): > > name = models.CharField(max_length=30) > > > def __unicode__(self): > > return self.name > > > class Meta: > > abstract = True > > > # > > --------------------------------------------------------------------------- > > ------- > > > class Page(models.Model): > > website = models.ForeignKey(Website) > > position = models.IntegerField() > > file_name = models.CharField(max_length=50) > > h1_title = models.CharField(max_length=50) > > > def __unicode__(self): > > return self.file_name > > > class Meta: > > ordering = ["file_name"] > > > # > > --------------------------------------------------------------------------- > > ------- > > > class PageItem(models.Model): > > page = models.ForeignKey(Page, editable=False) > > item = models.ForeignKey(Item) # WANT THIS TO POINT TO SPECIFIC > > SUBCLASS ITEM > > position = models.IntegerField() > > > def name(self): > > return str(self.item.name) > > > class Meta: > > ordering = ['position'] > > > # > > --------------------------------------------------------------------------- > > ------- > > > class RadioBoxType(Item): > > """A Radio Button object with its specific attributes""" > > ......... etc. > > > My problem is that I want the item/page relationship in the join table > > PageItem, so I can track the position. I realize that I can't have a > > fk to an abstract class though and obviously want it to point to the > > subclassed object. > > So point it at the subclass you want it to point at. > > If you mean, however, that you want it to point to one of a number of > possible subclasses, depending on the instance, then that isn't a > ForeignKey (a ForeignKey points to one particular model). What you're > modelling in that case is best done with the GenericForeignKey, since > that encodes both the content type (i.e. the model type) of the target > as well as the primary key value. > > Regards, > Malcolm --~--~---------~--~----~------------~-------~--~----~ 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 [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/django-users?hl=en -~----------~----~----~----~------~----~------~--~---
