Async ORM operations in Django - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What is the output of this async Django ORM query?

Consider the following async Django ORM code snippet. What will be the output when fetching the first user's username asynchronously?

Django

from django.contrib.auth.models import User
import asyncio

async def get_first_username():
    user = await User.objects.afirst()
    return user.username if user else 'No user'

result = asyncio.run(get_first_username())
print(result)

A Prints the username of the first user in the database

B Raises AttributeError because 'afirst' does not exist

C Prints 'No user' even if users exist

D Raises RuntimeError due to missing event loop

💡 Hint

Check if 'afirst()' is the correct async method to fetch the first object.

The afirst() method is the async version of first() in Django ORM. It fetches the first object asynchronously. If a user exists, it returns the username; otherwise, it returns 'No user'.

❓ state_output

intermediate

What is the value of 'count' after this async ORM operation?

Given the following async Django ORM code, what will be the value of count after execution?

Django

from myapp.models import Product
import asyncio

async def count_products():
    count = await Product.objects.acount()
    return count

count = asyncio.run(count_products())

A Always zero because async count is not supported

B Returns a coroutine object instead of an integer

C Raises TypeError due to incorrect await usage

D The total number of Product records in the database

💡 Hint

Remember that acount() is the async version of count().

The acount() method asynchronously returns the count of records matching the queryset. It returns an integer representing the total number of Product records.

📝 Syntax

advanced

Which option correctly performs an async filter query in Django ORM?

Select the code snippet that correctly filters users with email ending in '@example.com' asynchronously.

A users = await User.objects.filter(email__endswith='@example.com').aall()

B users = User.objects.filter(email__endswith='@example.com').aall()

C users = await User.objects.afilter(email__endswith='@example.com')

D users = await User.objects.filter(email__endswith='@example.com').all()

💡 Hint

Check which async queryset methods exist and how to await them.

The aall() method asynchronously evaluates the queryset and returns a list of results. You must await it. The afilter() method does not exist; filtering is synchronous but returns an async queryset that you can evaluate with aall().

🔧 Debug

advanced

Why does this async ORM code raise a RuntimeError?

Examine the code below. Why does it raise a RuntimeError: 'no running event loop'?

Django

from django.contrib.auth.models import User

async def get_users():
    return await User.objects.aall()

users = get_users()
print(users)

A Because 'print' cannot output async results

B Because the async function is called without an event loop using 'await' or 'asyncio.run()'

C Because 'aall()' is not a valid async method on QuerySet

D Because the User model does not support async queries

💡 Hint

How do you run async functions in Python scripts?

Async functions must be awaited inside an async context or run using asyncio.run(). Calling get_users() directly returns a coroutine, and printing it without awaiting causes a RuntimeError due to no running event loop.

🧠 Conceptual

expert

Which statement about Django async ORM operations is true?

Choose the correct statement about async ORM operations in Django.

A You can use async ORM methods without an async event loop in standard Django views

B Async ORM methods automatically convert synchronous queries to async without any performance difference

C Async ORM methods like 'aall()', 'aget()', and 'acount()' allow non-blocking database access in async views

D Async ORM methods replace all synchronous ORM methods and must be used exclusively

💡 Hint

Think about how async methods improve performance in async contexts.

Async ORM methods provide non-blocking database access, which is useful in async views to improve performance. They require an async event loop and do not replace synchronous methods entirely.