I have this setup in my models:
class Author(models.Model):
name = models.CharField(max_length=100)
class Topic(models.Model):
name = models.CharField(max_length=100)
class Article(models.Model):
name = models.CharField(max_length=100)
authors = models.ManyToManyField(Author, null=True, blank=True)
topics = models.ManyToManyField(Topic, null=True, blank=True)
Given an author, I want to know which topics he wrote about:
def author_info(request, pk):
author = get_object_or_404(Author, pk=pk)
topics = ????
If I had specified a through field, I could use that, but now Django makes the through field for me, and since its supposed to be transparent, Id rather not reference the field (unless there is a proper Django construction for that).
Use Lookups that span relationships:
topics = Topic.objects.filter(article__authors=author).distinct()
Note: you have to use distinct here, because the same topic can be selected by different articles.