Using Key in NDB to retrieve an entity

Question

I have this structure: Books that have Chapters (ancestor=Book) that have Pages (ancestor=Chapter)

It is clear for me that, to search for a Chapter by ID, I need the boo

Answer 1

You can do this in one go by doing an ancestor query, rather than a get:

chapter_key = ndb.Key('Book', long(bookId), 'Chapter', long(chapterId))
page = Page.query(Page.pageNumber==pageNumber, ancestor=chapter_key)