Custom error response models in FastAPI - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the correct FastAPI class.

FastAPI

from fastapi import [1]
app = [1]()

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

AFastAPI

BRequest

CResponse

DDepends

Attempts:

3 left

💡 Hint

Common Mistakes

Importing Request or Response instead of FastAPI.

Trying to create app with a wrong class.

You need to import FastAPI to create the app instance.

2fill in blank

medium

Complete the code to define a Pydantic model for error response with a message field.

FastAPI

from pydantic import BaseModel

class ErrorResponse([1]):
    message: str

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ABaseModel

BModel

CErrorModel

DResponseModel

Attempts:

3 left

💡 Hint

Common Mistakes

Using a wrong base class like Model or ResponseModel.

Forgetting to inherit from any class.

Pydantic models inherit from BaseModel to define data schemas.

3fill in blank

hard

Fix the error in the route decorator to specify the response model for errors.

FastAPI

@app.get("/items/{item_id}", responses={404: {"model": [1])
async def read_item(item_id: int):
    return {"item_id": item_id}

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AItem

BErrorResponse

CHTTPException

DResponse

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong model name like Item or Response.

Using an instance instead of the class.

The responses dictionary uses the error response model class name to describe the error schema.

4fill in blank

hard

Fill both blanks to raise an HTTPException with a custom error response model.

FastAPI

from fastapi import HTTPException

if not item:
    raise HTTPException(status_code=[1], detail=[2])

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

A404

B"Item not found"

C"Invalid request"

D500

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong status codes like 500 for not found.

Passing non-string detail values.

Use status code 404 for not found and a clear message string for detail.

5fill in blank

hard

Fill all three blanks to define a route that returns a custom error response model on failure.

FastAPI

from fastapi import status

@app.get("/users/{user_id}", responses=[1]: {"model": [2])
async def get_user(user_id: int):
    if user_id != 1:
        raise HTTPException(status_code=[3], detail="User not found")
    return {"user_id": user_id}

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

Astatus.HTTP_404_NOT_FOUND

BErrorResponse

C404

Dstatus.HTTP_400_BAD_REQUEST

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing status codes like 400 and 404.

Using string '404' instead of status constants.

Use the status code constant for 404, the error model class, and the same status code for the exception.