Why structured responses matter in FastAPI - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to return a JSON response with FastAPI.

FastAPI

from fastapi import FastAPI

app = FastAPI()

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

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

A{"item_id": item_id}

Bdict(item_id=item_id)

C[item_id]

Ditem_id

Attempts:

3 left

💡 Hint

Common Mistakes

Returning just the variable without a key

Returning a list instead of a dictionary

FastAPI expects a dictionary or Pydantic model to return structured JSON responses.

2fill in blank

medium

Complete the code to define a Pydantic model for structured response.

FastAPI

from pydantic import BaseModel

class Item(BaseModel):
    name: str
    price: float

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

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

AItem(name="Apple", price=1.2)

B{"name": "Apple", "price": 1.2}

Cdict(name="Apple", price=1.2)

D["Apple", 1.2]

Attempts:

3 left

💡 Hint

Common Mistakes

Returning a plain dictionary instead of the model instance

Returning a list instead of an object

Returning an instance of the Pydantic model ensures the response matches the declared schema.

3fill in blank

hard

Fix the error in the response to ensure consistent JSON structure.

FastAPI

from fastapi import FastAPI

app = FastAPI()

@app.get("/users/{user_id}")
async def read_user(user_id: int):
    if user_id == 1:
        return {"name": "Alice", "age": 30}
    else:
        return [1]

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

A["User not found"]

B"User not found"

C{"error": "User not found"}

DNone

Attempts:

3 left

💡 Hint

Common Mistakes

Returning a plain string or list breaks JSON structure

Returning None causes errors

Returning a dictionary with an error key keeps the response structure consistent.

4fill in blank

hard

Fill both blanks to create a consistent response with status code and message.

FastAPI

from fastapi import FastAPI
from fastapi.responses import JSONResponse

app = FastAPI()

@app.get("/status")
async def get_status():
    return JSONResponse(content=[1], status_code=[2])

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

A{"status": "ok"}

B200

C404

D{"error": "Not found"}

Attempts:

3 left

💡 Hint

Common Mistakes

Using a string instead of dictionary for content

Using wrong status codes for success

Use a dictionary for content and a valid HTTP status code for status_code.

5fill in blank

hard

Fill all three blanks to define a Pydantic model and return it in the response.

FastAPI

from pydantic import BaseModel
from fastapi import FastAPI

app = FastAPI()

class [1](BaseModel):
    title: str
    completed: bool

@app.get("/tasks/{task_id}", response_model=[2])
async def read_task(task_id: int):
    return [3](title="Learn FastAPI", completed=False)

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

ATask

DItem

Attempts:

3 left

💡 Hint

Common Mistakes

Using different names for model and response_model

Returning a dictionary instead of model instance

Define a model named Task and use it as the response_model and return its instance.