Connection pooling in FastAPI - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a connection pool with asyncpg in FastAPI.

FastAPI

import asyncpg

async def connect_db():
    pool = await asyncpg.create_pool(dsn=[1])
    return pool

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

A12345

B"postgresql://user:pass@localhost/dbname"

CNone

DTrue

Attempts:

3 left

💡 Hint

Common Mistakes

Using a number instead of a connection string

Passing None instead of a DSN string

The DSN (Data Source Name) string specifies the database connection details needed to create the pool.

2fill in blank

medium

Complete the code to acquire a connection from the pool in an async context.

FastAPI

async with pool.[1]() as connection:
    result = await connection.fetch('SELECT 1')

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

Aacquire

Bconnect

Cget

Dopen

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'connect' which creates a new connection

Using 'get' which is not a pool method

Use acquire() to get a connection from the pool safely in an async context.

3fill in blank

hard

Fix the error in the code to properly release the connection back to the pool.

FastAPI

connection = await pool.[1]()
try:
    await connection.execute('SELECT 1')
finally:
    await connection.release()

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

Aconnect

Bget

Copen

Dacquire

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'connect' which does not support release

Forgetting to release the connection

Use acquire() to get a connection that can be released back to the pool.

4fill in blank

hard

Fill both blanks to create a FastAPI dependency that provides a connection from the pool.

FastAPI

from fastapi import Depends

async def get_connection(pool=Depends([1])):
    async with pool.[2]() as conn:
        yield conn

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

Aconnect_db

Bacquire

Cconnect

Dget_pool

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'connect' instead of 'acquire'

Using a wrong dependency function name

The dependency connect_db provides the pool, and acquire() gets a connection from it.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that maps table names to their row counts using a connection.

FastAPI

counts = { [1]: await conn.fetchval(f'SELECT COUNT(*) FROM [2]') for [1] in [3] }

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

Atable

Bconn

Ctables

Dcount

Attempts:

3 left

💡 Hint

Common Mistakes

Using different names for loop variable and query placeholder

Using 'conn' as loop variable

We loop over tables with variable table and use it in the query string.