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17 / 30Django Models and Database DesignMediumPython - Django Framework

Coding: Bug Detection in Model Field Constraints

from django.db import models

class User(models.Model):
    email = models.EmailField(unique=True)
    username = models.CharField(max_length=100, blank=True, null=True)
    age = models.IntegerField(default=0)
    is_active = models.BooleanField(default=True)

user1 = User.objects.create(email="hari@example.com")
user2 = User.objects.create(email="hari@example.com")

  1. IntegrityError will be raised when attempting to create user2

  2. Both users will be created successfully with the same email

  3. The second user will be created with email set to None

  4. A ValidationError will be raised during model validation

Show answer & explanation

Correct answer

IntegrityError will be raised when attempting to create user2

Explanation

The code attempts to create two users with the same email address. Since email has unique=True, the second create() call will raise an IntegrityError because it violates the unique constraint on the email field.

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All 30 Django Models and Database Design questions

  1. 1.What is the primary purpose of Django Models?
  2. 2.Which field type should be used to store an email address in a Django Model?
  3. 3.What does the Meta class inside a Django Model do?
  4. 4.Which relationship type is used when one model can have many instances of another model?
  5. 5.What is the purpose of the `__str__` method in a Django Model?
  6. 6.Which field attribute makes a field mandatory in Django Models?
  7. 7.What does the `on_delete` parameter do in a ForeignKey relationship?
  8. 8.Which of the following is a valid Django field type for storing boolean values?
  9. 9.What is the default behavior when you don't specify `null=True` for a field in Django?
  10. 10.Which method is used to retrieve a single object from the database in Django?
  11. 11.Understanding Django Model Meta Options
  12. 12.Scenario:
  13. 13.Django QuerySet Filter vs Get Method
  14. 14.Coding:
  15. 15.Scenario:
  16. 16.Understanding Django Model Inheritance
  17. 17.Coding:
  18. 18.Scenario:
  19. 19.Django Model Manager and QuerySet Methods
  20. 20.Coding:
  21. 21.Django Model Inheritance Strategy Selection
  22. 22.Django QuerySet Optimization with select_related vs prefetch_related
  23. 23.Django Model Field Choices and Validation
  24. 24.Django Model Relationships:
  25. 25.Django Model Signals and Database Consistency
  26. 26.Django Model Meta Options:
  27. 27.Django Model Managers and Custom QuerySets
  28. 28.Django Model Field:
  29. 29.Django Model Validation:
  30. 30.Django Model Aggregation and Annotation