CODEWITHSUNDEEP
pythondjangoforeign-keysdatabase-relations
apelliciari
apelliciari

Reputation: 8501

Django: get related set from a related set of a model

class Book(models.Model):
    # fields

class Chapter(models.Model):
     book = models.ForeignKey(Book)

class Page(models.Model):
     chapter = models.ForeignKey(Chapter)

I want all the pages of the book A, possibly without cycling every chapter to fetch the pages.

book = Book.objects.get(pk=1)
pages = book.chapter_set.page_set #?!?

Upvotes: 9

Views: 3687

Answers (2)

Daniel Roseman
Daniel Roseman

Reputation: 599758

You can't do it that way. chapter_set is a query set, it doesn't have an attribute page_set.

Instead, turn it around:

Page.objects.filter(chapter__book=my_book)

Upvotes: 10

iMom0
iMom0

Reputation: 12931

When you query cross models, double underscores may help

book = Book.objects.get(pk=1)
pages = Page.objects.filter(chapter__book=book)

Upvotes: 4

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