Notice: This page requires JavaScript to function properly.
Please enable JavaScript in your browser settings or update your browser.
Lære ForeignKey Arguments | Relations
Django ORM Ninja: Advanced Techniques for Developers

bookForeignKey Arguments

To define a Many-to-One relation, models.ForeignKey is used. The first argument corresponds to the model to relate to, and the second, 'on_delete', specifies the behavior when the related object is deleted. The options include:

  • CASCADE: deleting a genre deletes all associated books;
  • PROTECT: prevents deletion if there are related books;
  • SET_NULL: sets the genre to Null if null=True in model definition;
  • SET_DEFAULT: sets a default value if the genre is deleted if there available some default value;
  • DO_NOTHING: no action, but may lead to IntegrityError.

The related_name argument in ForeignKey is useful for reverse relation from the Genre model back to Book model. If you don't specify a related_name, Django automatically creates one using the name of your model with the suffix _set (Genre.book_set.all()).

In our case works:

biography.books.all()  # provides all books of the given genre

Book.objects.filter(genre__format="history") # retrieve all books of the given genre

This structure provides a clear understanding of the Many-to-One relationship in Django, showcasing how to define and utilize it effectively.

1. What does 'models.ForeignKey' do in a Django model?

2. What happens when 'on_delete=models.CASCADE' is set in a ForeignKey relationship?

3. What is the purpose of the 'related_name' argument in a ForeignKey field?

question mark

What does 'models.ForeignKey' do in a Django model?

Select the correct answer

question mark

What happens when 'on_delete=models.CASCADE' is set in a ForeignKey relationship?

Select the correct answer

question mark

What is the purpose of the 'related_name' argument in a ForeignKey field?

Select the correct answer

Var alt klart?

Hvordan kan vi forbedre det?

Tak for dine kommentarer!

Sektion 4. Kapitel 2

Spørg AI

expand

Spørg AI

ChatGPT

Spørg om hvad som helst eller prøv et af de foreslåede spørgsmål for at starte vores chat

Awesome!

Completion rate improved to 3.57

bookForeignKey Arguments

Stryg for at vise menuen

To define a Many-to-One relation, models.ForeignKey is used. The first argument corresponds to the model to relate to, and the second, 'on_delete', specifies the behavior when the related object is deleted. The options include:

  • CASCADE: deleting a genre deletes all associated books;
  • PROTECT: prevents deletion if there are related books;
  • SET_NULL: sets the genre to Null if null=True in model definition;
  • SET_DEFAULT: sets a default value if the genre is deleted if there available some default value;
  • DO_NOTHING: no action, but may lead to IntegrityError.

The related_name argument in ForeignKey is useful for reverse relation from the Genre model back to Book model. If you don't specify a related_name, Django automatically creates one using the name of your model with the suffix _set (Genre.book_set.all()).

In our case works:

biography.books.all()  # provides all books of the given genre

Book.objects.filter(genre__format="history") # retrieve all books of the given genre

This structure provides a clear understanding of the Many-to-One relationship in Django, showcasing how to define and utilize it effectively.

1. What does 'models.ForeignKey' do in a Django model?

2. What happens when 'on_delete=models.CASCADE' is set in a ForeignKey relationship?

3. What is the purpose of the 'related_name' argument in a ForeignKey field?

question mark

What does 'models.ForeignKey' do in a Django model?

Select the correct answer

question mark

What happens when 'on_delete=models.CASCADE' is set in a ForeignKey relationship?

Select the correct answer

question mark

What is the purpose of the 'related_name' argument in a ForeignKey field?

Select the correct answer

Var alt klart?

Hvordan kan vi forbedre det?

Tak for dine kommentarer!

Sektion 4. Kapitel 2
some-alt