[Solved] Why does this code raise an error?queryset = Book.objects.prefetch_related('author.books') — Ans: Because 'author.books' is a nested prefetch and requires Prefetch object. | Django

Django - Caching

Why does this code raise an error?

queryset = Book.objects.prefetch_related('author.books')

ABecause 'author.books' is a nested prefetch and requires Prefetch object.

BBecause prefetch_related does not accept strings with dots.

CBecause 'author' is not a reverse relation.

DBecause Book model has no 'author' field.

Step-by-Step Solution

Solution:

Step 1: Understand nested prefetching
To prefetch nested relations like 'author.books', you must use Prefetch objects.
Step 2: Check prefetch_related argument rules
Simple strings cannot express nested prefetch; this causes an error.
Final Answer:
Because 'author.books' is a nested prefetch and requires Prefetch object. -> Option A
Quick Check:
Nested prefetch needs Prefetch object = B [OK]

Quick Trick: Use Prefetch objects for nested reverse relation prefetching [OK]

Common Mistakes:

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