Hello, the answer for question 1 I already find out, thank you.
According to question 2, I'm not meaning without a relation between A and B. There must be a relation between them. So I describe my problem again in a more understandable way, I hope. I have two models A and B with an one(A)-to-many(B) relationship. So I want to build a view for adding a B, which is related to a A. For that I have a link in another view. That Link contains the ID of A. So in the new view I knew the ID of A, which should be related with the new B. How I get B related with A? (Ok, by setting the attribute, but...) How can I do that by using form_for_model() according to my database model? The User don't have the choice to manipulate the ID of A or something like that. There shouldn't be a field for the ID! On 16 Mai, 22:52, "Richard Dahl" <[EMAIL PROTECTED]> wrote: > For the first question, the db-api doc should provide this and more > information, as I am not sure I completely understand, but here goes > (assuming the following models): > > class B(models.Model): > attribute = char()... > > class A(models.Model): > attribute = char()... > bs = m2m(B) > > in your view to get all of the B(s) related to a given A > > a = A.objects.get(pk=1) > b = a.bs.all() > > if you want to get all of the Bs that are related to 'any' A: > b = B.objects.filter(a__isnull = False) > > for question 2, I am not sure what you mean, if you mean can you create a B > without relating it to an A? sure, a related A is not required by B. If you > do not want to require a B for A just set 'blank=True, null=True' in the M2M > field definition in A. > > Not sure if this helps, your original post was somewhat confusing, if you > post relevant snippets from your models you may get more intelligent > responses than my intellectual meanderings. > -richard > > On 5/16/08, jabbercat <[EMAIL PROTECTED]> wrote: > > > > > > > > > Hello, > > > it's my frist time I'm using this Group. > > > My Problems: > > I have a class A and a class B with a one(A)-to-many(B) relationship > > between them. > > > My first question: Is there an efficient way to get in a template all > > instances of B, which are related to an instance of A, when i only > > knew an instance of A? Something like a special attribute, or > > something like that? > > > My second question: I want to use form_for_model(), because of my > > database-driver design. But how can I add an instance of B so that the > > relation to an instance of A is also saved, without specify the > > foreign key id of A explicitly? > > > I hope you understand what I meen. --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
