that works (to my surprise). thanks a lot. Am 04.10.2006 um 18:49 schrieb DavidA:
> > > va:patrick.kranzlmueller wrote: >> I have a model with blog-postings, assigned to a specific user - the >> user is stored in the table "posting" via foreignkey. >> >> the user is part of a grade, part of a school and part of a state - >> all of which have overview-pages. >> so, to get all the postings for a state I have to do the following: >> >> 1. search for schools in that state >> 2. search for grades in that school >> 3. search for users within that grade >> 4. and finally, get all the postings for that user >> >> seems a little complicated. > > Not sure if I understand your models exactly, but you don't need to do > four "searches" (queries), you just need to do one query with the > constraint that spans the four relations. Assuming your models look > something like this: > > class State(models.Model): > code = models.CharField(maxlength=2) > > class School(models.Model): > state = models.ForeignKey(State) > > class Grade(models.Model): > school = models.ForeignKey(School) > > class User(models.Model): > grade = models.ForeignKey(Grade) > > class Posting(models.Model): > user = models.ForeignKey(User) > > Then you can just do this to find all postings for users in grades in > schools in New York: > > Posting.objects.filter(user__grade__school__state__code='NY') > > Which will translate into one query looking something like this: > > select * from posting > join user on posting.user_id = user.id > join grade on user.grade_id = grade.id > join school on grade.school_id = school.id > join state on school.state_id = state.id > where state.code = 'NY' > > (abbreviated - the actual Django version of the SQL will be quite a > bit > more verbose due to fully qualified column names). > > Of course, I may have completely misunderstood your models and this > may > be completely off base! > -Dave > > > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Django users" 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/django-users -~----------~----~----~----~------~----~------~--~---
