pre_save and post_save signals in Django - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the Django signal used before saving a model instance.

Django

from django.db.models.signals import [1]

Drag options to blanks, or click blank then click option'

Apre_save

Bpost_save

Cm2m_changed

Drequest_finished

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing pre_save with post_save.

Importing unrelated signals like m2m_changed.

The pre_save signal is sent just before a model's save() method is called.

2fill in blank

medium

Complete the code to connect a function to the post_save signal for a model named Book.

Django

post_save.connect([1], sender=Book)

Drag options to blanks, or click blank then click option'

Asave_book

Bbook_saved_handler

Chandle_save

Dpost_save

Attempts:

3 left

💡 Hint

Common Mistakes

Using the signal name instead of a handler function.

Passing a string instead of a function reference.

The function connected to a signal should be a handler that processes the event, here named book_saved_handler.

3fill in blank

hard

Fix the error in the signal handler definition to accept the correct parameters.

Django

def [1](sender, instance, **kwargs):
    print(f"Saved: {instance}")

Drag options to blanks, or click blank then click option'

Apre_save_handler

Bpost_save

Cbook_saved_handler

Dhandle_save

Attempts:

3 left

💡 Hint

Common Mistakes

Using the signal name as the function name.

Mismatching handler names between connection and definition.

The handler function name should match the one connected to the signal, here book_saved_handler.

4fill in blank

hard

Fill both blanks to define a pre_save signal handler that modifies a model's field before saving.

Django

def [1](sender, instance, **kwargs):
    instance.title = instance.title.[2]()

Drag options to blanks, or click blank then click option'

Apre_save_handler

Bpost_save_handler

Cupper

Dlower

Attempts:

3 left

💡 Hint

Common Mistakes

Using post_save handler name for pre_save.

Using wrong string method like lower instead of upper.

The handler pre_save_handler modifies the title field to uppercase before saving.

5fill in blank

hard

Fill all three blanks to connect a pre_save handler and ensure it only runs for the Author model.

Django

from django.db.models.signals import [1]

[2].connect(pre_save_handler, sender=[3])

Drag options to blanks, or click blank then click option'

Apre_save

Bpost_save

CAuthor

DBook

Attempts:

3 left

💡 Hint

Common Mistakes

Importing or connecting the wrong signal.

Connecting the handler to the wrong model.

The pre_save signal is imported and used to connect pre_save_handler for the Author model only.