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

ForeignKey ArgumentsForeignKey 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:

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?

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

Select the correct answer

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

Select the correct answer

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

Select the correct answer

Everything was clear?

Section 4. Chapter 2
course content

Course Content

Django ORM Ninja: Advanced Techniques for Developers

1. Introduction to Django ORM

Introduction to the CourseIntroduction to the ORMStart a New ProjectInitialize a New Project

2. Models, datatypes, and fields

Defining The First ModelField Data TypesDefine Other ModelsMigrationsAdmin Interface

3. Queries

Create QueryRetrieve QueryLazy QueriesOrdering and SlicingUpdatingDeleting

4. Relations

Many-to-OneForeignKey ArgumentsOne-to-OneMany-to-Many

5. Complex Queries

Field LookupsQ and F ObjectsAggregationsAnnotationsMinimazing Database Hints

6. Advanced

Class MetaConstrainsTransactions BasicsUser Model

Django ORM Ninja: Advanced Techniques for Developers

ForeignKey ArgumentsForeignKey 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:

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?

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

Select the correct answer

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

Select the correct answer

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

Select the correct answer

Everything was clear?

Section 4. Chapter 2
some-alt