# Django Signals (Django)

> Built-in signals, pre_save, post_save, pre_delete, custom signals, receivers, signal best practices

- 18 interview questions
- Mid-Level
- [Interview Questions: Django](https://sharpskill.dev/en/technologies/django/interview-questions.md)

## 1. What is a signal in Django?

**Answer**

A signal is a mechanism allowing certain parts of the application to be notified when specific actions occur elsewhere in the framework. Signals enable decoupling between the event sender and the receivers that react to that event. Django provides several built-in signals like pre_save, post_save, pre_delete and post_delete for model operations.

## 2. Which signal is emitted just before an object is saved to the database?

**Answer**

The pre_save signal is emitted before a model's save() method is executed. It allows making modifications to the instance before it is saved, such as calculating derived values or normalizing data. This signal is useful because it is called whether the object is being created or updated.

## 3. Which decorator should be used to connect a receiver function to a Django signal?

**Answer**

The @receiver decorator from django.dispatch allows connecting a function to a signal declaratively. It takes the signal to listen to as a parameter and optionally the sender to filter emitters. This approach is more readable than the connect() method and makes code maintenance easier.

## 15 more questions available

- Which argument of the post_save signal allows distinguishing a creation from an update?
- Where is it recommended to place signal receiver code in a Django application?

Sign up for free: https://sharpskill.dev/en/login

## Other Django interview topics

- [Python Basics](https://sharpskill.dev/en/technologies/django/interview-questions/python-basics.md): 25 questions, Junior
- [Python OOP](https://sharpskill.dev/en/technologies/django/interview-questions/python-oop.md): 20 questions, Junior
- [Django Fundamentals](https://sharpskill.dev/en/technologies/django/interview-questions/django-fundamentals.md): 20 questions, Junior
- [Django Models - Basics](https://sharpskill.dev/en/technologies/django/interview-questions/django-models-basics.md): 22 questions, Junior
- [Django Views](https://sharpskill.dev/en/technologies/django/interview-questions/django-views.md): 20 questions, Junior
- [Django Templates](https://sharpskill.dev/en/technologies/django/interview-questions/django-templates.md): 18 questions, Junior
- [Django Forms](https://sharpskill.dev/en/technologies/django/interview-questions/django-forms.md): 22 questions, Mid-Level
- [Advanced QuerySets](https://sharpskill.dev/en/technologies/django/interview-questions/django-querysets.md): 25 questions, Mid-Level
- [Django Authentication](https://sharpskill.dev/en/technologies/django/interview-questions/django-authentication.md): 22 questions, Mid-Level
- [Django Middleware](https://sharpskill.dev/en/technologies/django/interview-questions/django-middleware.md): 18 questions, Mid-Level
- [Django Admin](https://sharpskill.dev/en/technologies/django/interview-questions/django-admin.md): 20 questions, Mid-Level
- [Django REST Framework](https://sharpskill.dev/en/technologies/django/interview-questions/django-rest-framework.md): 30 questions, Mid-Level
- [File Upload](https://sharpskill.dev/en/technologies/django/interview-questions/django-file-upload.md): 20 questions, Mid-Level
- [Django Caching](https://sharpskill.dev/en/technologies/django/interview-questions/django-caching.md): 20 questions, Mid-Level
- [Django Sessions](https://sharpskill.dev/en/technologies/django/interview-questions/django-sessions.md): 18 questions, Mid-Level
- [Django Email](https://sharpskill.dev/en/technologies/django/interview-questions/django-email.md): 18 questions, Mid-Level
- [Django Testing](https://sharpskill.dev/en/technologies/django/interview-questions/django-testing.md): 22 questions, Mid-Level
- [Django Security](https://sharpskill.dev/en/technologies/django/interview-questions/django-security.md): 22 questions, Mid-Level
- [Django Deployment](https://sharpskill.dev/en/technologies/django/interview-questions/django-deployment.md): 24 questions, Mid-Level
- [Advanced Django ORM](https://sharpskill.dev/en/technologies/django/interview-questions/django-orm-advanced.md): 28 questions, Senior
- [Django Performance](https://sharpskill.dev/en/technologies/django/interview-questions/django-performance.md): 24 questions, Senior
- [Django & Celery](https://sharpskill.dev/en/technologies/django/interview-questions/django-celery.md): 22 questions, Senior
- [Django Channels](https://sharpskill.dev/en/technologies/django/interview-questions/django-channels.md): 24 questions, Senior
- [Django & GraphQL](https://sharpskill.dev/en/technologies/django/interview-questions/django-graphql.md): 24 questions, Senior
- [Django & Docker](https://sharpskill.dev/en/technologies/django/interview-questions/django-docker.md): 20 questions, Senior
- [Django in Microservices Ecosystem](https://sharpskill.dev/en/technologies/django/interview-questions/django-microservices.md): 24 questions, Senior
- [Custom Django Commands](https://sharpskill.dev/en/technologies/django/interview-questions/django-custom-commands.md): 18 questions, Senior
- [Django Internationalization](https://sharpskill.dev/en/technologies/django/interview-questions/django-internationalization.md): 20 questions, Senior
- [Django Design Patterns](https://sharpskill.dev/en/technologies/django/interview-questions/django-design-patterns.md): 24 questions, Senior
- [Django Async & ASGI](https://sharpskill.dev/en/technologies/django/interview-questions/django-async-asgi.md): 26 questions, Senior
- [Settings & Production Configuration](https://sharpskill.dev/en/technologies/django/interview-questions/django-settings-configuration.md): 22 questions, Senior
- [Observability & Monitoring](https://sharpskill.dev/en/technologies/django/interview-questions/django-observability.md): 24 questions, Senior

---

Source: SharpSkill (https://sharpskill.dev), tech interview preparation for your real stack.
HTML version of this page: https://sharpskill.dev/en/technologies/django/interview-questions/django-signals