Custom middleware creation in FastAPI - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the base class for middleware in FastAPI.

FastAPI

from starlette.middleware.base import [1]

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

ABaseHTTPMiddleware

BMiddleware

CRequestMiddleware

DCustomMiddleware

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'Middleware' which is a different concept.

Trying to import a non-existent 'RequestMiddleware'.

The BaseHTTPMiddleware class is the base class used to create custom middleware in FastAPI.

2fill in blank

medium

Complete the code to define the async method that processes each request in custom middleware.

FastAPI

class CustomMiddleware(BaseHTTPMiddleware):
    async def [1](self, request, call_next):
        response = await call_next(request)
        return response

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

Aprocess_request

Bmiddleware_call

Chandle

Ddispatch

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'process_request' which is not recognized by FastAPI middleware.

Naming the method 'handle' or 'middleware_call' which are incorrect.

The dispatch method is the required async method to process requests in FastAPI custom middleware.

3fill in blank

hard

Fix the error in the middleware code by completing the missing import for the Request class.

FastAPI

from fastapi import FastAPI
from starlette.middleware.base import BaseHTTPMiddleware
from starlette.requests import [1]

app = FastAPI()

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

AMiddleware

BResponse

CRequest

DHTTPMiddleware

Attempts:

3 left

💡 Hint

Common Mistakes

Importing 'Response' instead of 'Request'.

Trying to import 'Middleware' which is not a class here.

The Request class from starlette.requests is needed to type hint or use the request object in middleware.

4fill in blank

hard

Fill both blanks to add the custom middleware to the FastAPI app.

FastAPI

app = FastAPI()
app.add_middleware([1], app=[2])

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

ACustomMiddleware

BBaseHTTPMiddleware

Cmiddleware_class

Dapp

Attempts:

3 left

💡 Hint

Common Mistakes

Passing BaseHTTPMiddleware directly instead of the custom class.

Passing a wrong keyword argument name or value.

You add your custom middleware class CustomMiddleware to the app using add_middleware, passing the app instance as a parameter.

5fill in blank

hard

Fill all three blanks to modify the response headers inside the custom middleware.

FastAPI

class CustomMiddleware(BaseHTTPMiddleware):
    async def dispatch(self, request, call_next):
        response = await call_next(request)
        response.headers[[1]] = [2]
        response.headers[[3]] = "CustomValue"
        return response

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

A"X-Custom-Header"

B"Processed"

C"X-Another-Header"

D"Ignored"

Attempts:

3 left

💡 Hint

Common Mistakes

Using non-string keys or values for headers.

Mixing header names and values in the wrong blanks.

To add custom headers, you assign header names and values to response.headers. Here, "X-Custom-Header" and "X-Another-Header" are header names, and "Processed" is a header value.