Well django has a ISNULL which I guess could be use to get the result that you want. I'm a bit new to django and have not done any many-to- many relationships as yeah but I'm guessing you could do something like this:
Lest say table A = Blog, B = entry and C = blogentry Blog.objects.filter(entry__isnull=True) If I am correct this should return a list of blogs that does not have any entires. On Dec 7, 12:06 am, Wes Wagner <wes.wag...@gmail.com> wrote: > This is a generic question because I am a newbie and things are not > gelling quite 100% on how to write Q statements to get a filter to do > everything one wants. > > Let's say you have Table A and Table B and Table C, where Table B has > a foreign key to table A and Table C (a manually constructed many to > many because it has extra data elements) > > Now I want to build a list of all elements from table A, where not > exists a record in Table B that is related to table A and also has a > couple values = to something, and related to a particular table C > record) > > In SQL this would look like: > > select * from a where not exists (select * from B,C where > a.id=b.aforeignkey and c.id=b.cforeignkey and b.filter1=blah and > c.filter2=blah) > > How does that look when you are building an object list in the Q( )... > style format? Where I am hung up is finding syntax examples of how to > do the functional equivalent of a sql where not exists clause. > > Is there a way to do this without using .extra() and using just normal > django? > > -Wes Wagner -- You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-us...@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.
