all() and filter() methods in Django - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What does Model.objects.all() return?

In Django, when you call Model.objects.all(), what type of object do you get back?

A A list of dictionaries representing each record.

B A QuerySet containing all records of the Model in the database.

C A single Model instance representing the first record.

D An integer count of all records in the Model.

💡 Hint

Think about what Django returns to let you work with multiple records easily.

Model.objects.all() returns a QuerySet that contains all records of that model. It is lazy and can be further filtered or iterated.

❓ component_behavior

intermediate

What does Model.objects.filter(field=value) return?

In Django, what does Model.objects.filter(field=value) return?

A A QuerySet with all records where <code>field</code> equals <code>value</code>.

B A single Model instance where <code>field</code> equals <code>value</code>.

C A boolean indicating if any record matches <code>field=value</code>.

D A list of primary keys of matching records.

💡 Hint

Remember, filter narrows down records but still returns multiple if found.

filter() returns a QuerySet of all records matching the condition. It can be empty if no matches.

❓ state_output

advanced

What is the output of this Django QuerySet code?

Given the following Django model and code, what is the output of print(qs.count())?

Django

from django.db import models

class Product(models.Model):
    name = models.CharField(max_length=100)
    price = models.DecimalField(max_digits=6, decimal_places=2)

# Assume database has 3 products: 
# Product(name='Pen', price=1.50), Product(name='Book', price=10.00), Product(name='Notebook', price=5.00)

qs = Product.objects.filter(price__gt=5.00)
print(qs.count())

A 2

B 3

C 1

D 0

💡 Hint

Look at which products have price greater than 5.00.

Only 'Book' (10.00) and 'Notebook' (5.00) are checked. Since price__gt means strictly greater than 5.00, 'Notebook' is excluded. So only 'Book' counts.

📝 Syntax

advanced

Which option causes a syntax error in Django QuerySet filtering?

Which of the following Django QuerySet filter calls will cause a syntax error?

A Model.objects.filter(active=True)

B Model.objects.filter(price__gte=10, price__lte=20)

C Model.objects.filter('name'='test')

D Model.objects.filter(name__icontains='test')

💡 Hint

Check how keyword arguments are passed in Python functions.

Option C uses quotes around the keyword argument which is invalid syntax in Python function calls.

🔧 Debug

expert

Why does this Django QuerySet filter return no results?

Given this code, why does qs return an empty QuerySet?

Django

qs = Product.objects.filter(name__startswith='Pen', price__lt=1.00)

A The <code>startswith</code> lookup is case-sensitive and no product matches.

B The filter syntax is incorrect and causes a runtime error.

C The database connection is lost, so no results are returned.

D No products have a name starting with 'Pen' and price less than 1.00 at the same time.

💡 Hint

Think about the conditions combined with AND logic in filter.

Filters combine conditions with AND logic. If no product matches both conditions simultaneously, the QuerySet is empty.