Variables and types

Python variables bind names to objects—no int x = 5 declarations. Django settings, model fields, and view context all use Python's dynamic typing with optional type hints in modern codebases.

Common types in Django code

• str — titles, slugs, CharField values
• int — primary keys, counts, IntegerField
• bool — flags, BooleanField, permission checks
• list, dict — querysets converted to lists, template context
• None — missing optional fields, empty querysets

Truthy and falsy

Empty strings, empty lists, 0, and None are falsy—useful in templates and if queryset: checks. A queryset with rows is truthy even before you iterate.

Important interview questions and answers

1. Q: Mutable vs immutable in Django?
   A: Strings and tuples are immutable; lists and dicts are mutable—avoid mutating shared default arguments in model methods.
2. Q: What type is a model instance?
   A: An instance of your model class (subclass of models.Model), not a plain dict.
3. Q: Type hints in Django?
   A: Optional but growing—helps IDEs and mypy in larger codebases.

Self-check

1. Which values are falsy in Python?
2. What type does Article.objects.count() return?