Path operation dependencies in FastAPI - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the dependency function from FastAPI.

FastAPI

from fastapi import [1]

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

AResponse

BRequest

CDepends

DPath

Attempts:

3 left

💡 Hint

Common Mistakes

Importing Request or Response instead of Depends.

Using Path instead of Depends for dependencies.

The Depends function is used to declare dependencies in FastAPI path operations.

2fill in blank

medium

Complete the code to declare a dependency function that returns a string.

FastAPI

def get_token():
    return [1]

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A12345

BNone

Ctoken123

D'token123'

Attempts:

3 left

💡 Hint

Common Mistakes

Returning a number instead of a string.

Returning an unquoted string which causes a NameError.

The function should return a string, so the value must be in quotes.

3fill in blank

hard

Fix the error in the path operation to use the dependency correctly.

FastAPI

from fastapi import FastAPI, Depends

app = FastAPI()

def get_token():
    return 'token123'

@app.get("/items/")
async def read_items(token: str = [1]):
    return {"token": token}

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ADepends(get_token)

Bget_token

CDepends

Dget_token()

Attempts:

3 left

💡 Hint

Common Mistakes

Using the function name without Depends.

Calling the function directly instead of passing it to Depends.

To declare a dependency, use Depends(get_token) so FastAPI knows to call the function and inject its result.

4fill in blank

hard

Fill both blanks to declare a dependency that extracts a query parameter and use it in the path operation.

FastAPI

from fastapi import FastAPI, Depends, Query

app = FastAPI()

def get_limit(limit: int = [1]):
    return limit

@app.get("/items/")
async def read_items(limit: int = [2]):
    return {"limit": limit}

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AQuery(10)

BDepends(get_limit)

CQuery()

DDepends(Query(10))

Attempts:

3 left

💡 Hint

Common Mistakes

Not using Query in the dependency function parameter.

Not using Depends in the path operation parameter.

The dependency function uses Query(10) to set a default query parameter. The path operation uses Depends(get_limit) to get the value from the dependency.

5fill in blank

hard

Fill all three blanks to create a dependency that checks a header and use it in a path operation.

FastAPI

from fastapi import FastAPI, Depends, Header, HTTPException

app = FastAPI()

def verify_token(x_token: str = [1]):
    if x_token != "fake-super-secret-token":
        raise HTTPException(status_code=401, detail="Invalid token")
    return x_token

@app.get("/secure-data")
async def secure_data(token: str = [2]):
    return {"token": [3]

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AHeader(...)

BDepends(verify_token)

Ctoken

DHeader(None)

Attempts:

3 left

💡 Hint

Common Mistakes

Using Header(None) which makes the header optional.

Not using Depends in the path operation parameter.

Returning the wrong variable in the response.

The dependency function uses Header(...) to require the header. The path operation uses Depends(verify_token) to call the dependency. The returned token is then used in the response.