Thanks for your input, Bill, I appreciate it. I think I'm just going to take a hit and switch to an explicit OneToOneField instead of trying to make this work with inheritance. The other way things will just work, because django's built to make it work, but doing it with inheritance is difficult and ugly. Thanks for helping me see that. I wonder if it's worth putting a note in the django docs that in some cases a OneToOneField is more appropriate than inheritance, given some of these problems (and the fact that other people have had the same problem, as I noted with my link to a previous post to django-users). Anyway, thanks again for your help.
Matt On Thu, Jun 23, 2011 at 3:47 PM, Bill Freeman <ke1g...@gmail.com> wrote: > So, we're talking about "Multi-table inheritance" > ( > https://docs.djangoproject.com/en/1.3/topics/db/models/#multi-table-inheritance > ). > Note that this uses "an automatically-created OneToOneField". > > What you really want to do is to create a python instance of the Verb > class. It's id (in the Verb table) will be empty, meaning the Verb > row will get created on save(). If the field that Verb uses to refer > to Word is already set at save() time, the ORM *MIGHT* just happily > save Verb, and either not save the unmodified Word (I'm pretty sure > that you must have an instantiation of the Word instance lying > around), or, at worst, just update it with unchanged data, rather than > creating a new instance. You'll have to experiment, unless an ORM > expert speaks up. > > One problem is how to set that reference in the Verb object. I don't > think you get a 'word' attribute on a Verb object, do you? If worst > comes to worse you can access the attribute by using > v.__dict__['attribute_name'] where v is a Verb instance. You can poke > around in pdb on a Verb instance that was made and already saved in > the normal way to see how things are named and represented. > > You are probably on your own to assure that you don't add more than > one Verb to a given Word. Some of the reverse lookup stuff may get > confused if there are more than one. I doubt that the uniqueness > constraint in the DB functions in that direction. Beware multiple > threads - you may need to play with transactions and roll backs. > > And, of course, things could change in a future version even if this works > now. > > Good luck, Bill > > On Thu, Jun 23, 2011 at 2:22 PM, Matthew Gardner <mj...@byu.edu> wrote: > > On Thu, Jun 23, 2011 at 2:18 PM, Matthew Gardner <mj...@byu.edu> wrote: > >> > >> class Verb(models.Model): > >> word = models.ForeignKey('Word') > >> # Verb-specific stuff > > > > Sorry, this is more accurate: > > class Verb(models.Model): > > word = models.OneToOneField('Word') > > # verb-specific stuff > > > > -- > > 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. > > > > -- > 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. > > -- 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.
