Class-based dependencies in FastAPI - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a class-based dependency in FastAPI.

FastAPI

from fastapi import Depends, FastAPI

class CommonQueryParams:
    def __init__(self, q: str = None):
        self.q = q

app = FastAPI()

@app.get("/items/")
async def read_items(commons: CommonQueryParams = Depends([1])):
    return {"q": commons.q}

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

ADepends(CommonQueryParams)

BCommonQueryParams()

CCommonQueryParams

DDepends(CommonQueryParams())

Attempts:

3 left

💡 Hint

Common Mistakes

Passing an instance of the class instead of the class itself.

Wrapping Depends around an instance instead of the class.

In FastAPI, to use a class as a dependency, you pass the class itself (not an instance) to Depends(). FastAPI will create an instance automatically.

2fill in blank

medium

Complete the code to inject a class-based dependency into a path operation.

FastAPI

from fastapi import Depends, FastAPI

class User:
    def __init__(self, username: str):
        self.username = username

app = FastAPI()

@app.get("/users/me")
async def read_user(user: User = Depends([1])):
    return {"username": user.username}

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AUser

BUser()

CDepends(User())

DDepends(User)

Attempts:

3 left

💡 Hint

Common Mistakes

Passing an instance instead of the class.

Using Depends with an instance instead of the class.

Pass the class name to Depends without parentheses. FastAPI will create the instance and inject it.

3fill in blank

hard

Fix the error in the class-based dependency usage.

FastAPI

from fastapi import Depends, FastAPI

class Settings:
    def __init__(self):
        self.debug = True

app = FastAPI()

@app.get("/settings")
async def get_settings(settings: Settings = Depends([1])):
    return {"debug": settings.debug}

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ASettings

BSettings()

CDepends(Settings())

DDepends(Settings)

Attempts:

3 left

💡 Hint

Common Mistakes

Passing an instance instead of the class.

Wrapping Depends around an instance.

Pass the class name to Depends without parentheses. FastAPI will instantiate it automatically.

4fill in blank

hard

Fill both blanks to create a class-based dependency that accepts a query parameter and use it in a path operation.

FastAPI

from fastapi import Depends, FastAPI

class QueryParams:
    def __init__(self, q: str = None):
        self.q = q

app = FastAPI()

@app.get("/search")
async def search(params: QueryParams = Depends([1])):
    return {"query": params.[2]

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AQueryParams

Bquery

Cq

DQueryParams()

Attempts:

3 left

💡 Hint

Common Mistakes

Passing an instance instead of the class.

Using the wrong attribute name for the query parameter.

Pass the class name to Depends. The instance has an attribute 'q' holding the query parameter.

5fill in blank

hard

Fill all three blanks to create a class-based dependency with two parameters and use them in a path operation.

FastAPI

from fastapi import Depends, FastAPI

class Pagination:
    def __init__(self, skip: int = 0, limit: int = 10):
        self.skip = skip
        self.limit = limit

app = FastAPI()

@app.get("/items")
async def list_items(pagination: Pagination = Depends([1])):
    return {"skip": pagination.[2], "limit": pagination.[3]

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

APagination

Bskip

Climit

DPagination()

Attempts:

3 left

💡 Hint

Common Mistakes

Passing an instance instead of the class.

Using incorrect attribute names for pagination.

Pass the class name to Depends. Access the 'skip' and 'limit' attributes from the instance.