Solution:Step 1: Understand nested select_relatedTo fetch related objects across multiple foreign keys, use double underscores to traverse relations.Step 2: Analyze optionsBook.objects.select_related('author', 'author__publisher').all() correctly uses 'author' and 'author__publisher' to join both re

[Solved] Given these models:class Publisher(models.Model): name = models.CharField(max_length=100) class Author(models.Model): name = models.CharField(max_length=100) publisher = models.... | Django

Django - Caching

Given these models:

class Publisher(models.Model):
    name = models.CharField(max_length=100)

class Author(models.Model):
    name = models.CharField(max_length=100)
    publisher = models.ForeignKey(Publisher, on_delete=models.CASCADE)

class Book(models.Model):
    title = models.CharField(max_length=100)
    author = models.ForeignKey(Author, on_delete=models.CASCADE)

Which select_related call will efficiently fetch Book objects with their related Author and Publisher in one query?

ABook.objects.select_related('publisher').all()

BBook.objects.select_related('author.publisher').all()

CBook.objects.prefetch_related('author', 'publisher').all()

DBook.objects.select_related('author', 'author__publisher').all()

Step-by-Step Solution

Solution:

Step 1: Understand nested select_related
To fetch related objects across multiple foreign keys, use double underscores to traverse relations.
Step 2: Analyze options
Book.objects.select_related('author', 'author__publisher').all() correctly uses 'author' and 'author__publisher' to join both related models. Book.objects.select_related('author.publisher').all() uses incorrect dot notation. Book.objects.prefetch_related('author', 'publisher').all() uses prefetch_related which is less efficient for ForeignKey. Book.objects.select_related('publisher').all() tries to select a non-existent direct field.
Final Answer:
Book.objects.select_related('author', 'author__publisher').all() -> Option D
Quick Check:
Is nested relation syntax with double underscores correct? Yes. [OK]

Quick Trick: Use double underscores for nested select_related fields [OK]

Common Mistakes:

MISTAKES

Using dot notation instead of double underscores
Trying to select_related non-foreign key fields
Using prefetch_related for ForeignKey relations

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Given these models:

Step 1: Understand nested select_related

Step 2: Analyze options

Final Answer:

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