Including routers in main app in FastAPI - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import FastAPI and create an app instance.

FastAPI

from fastapi import [1]

app = [1]()

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

ARequest

BFastAPI

CAPIRouter

DDepends

Attempts:

3 left

💡 Hint

Common Mistakes

Importing APIRouter instead of FastAPI

Forgetting to call FastAPI() as a function

FastAPI is the main class to create the app instance.

2fill in blank

medium

Complete the code to import APIRouter and create a router instance.

FastAPI

from fastapi import [1]

router = [1]()

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

AAPIRouter

BRequest

CDepends

DFastAPI

Attempts:

3 left

💡 Hint

Common Mistakes

Importing FastAPI instead of APIRouter

Not calling APIRouter() as a function

APIRouter is used to create a router instance for grouping routes.

3fill in blank

hard

Fix the error in including the router in the main app.

FastAPI

app = FastAPI()

app.[1](router)

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

Aregister_router

Badd_router

Cinclude_router

Dattach_router

Attempts:

3 left

💡 Hint

Common Mistakes

Using add_router instead of include_router

Using register_router or attach_router which do not exist

The correct method to add a router to the app is include_router.

4fill in blank

hard

Fill both blanks to define a route in the router and include it in the app.

FastAPI

from fastapi import FastAPI, APIRouter

router = APIRouter()

@router.[1]("/")
async def root():
    return {"message": "Hello"}

app = FastAPI()
app.[2](router)

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

Aget

Binclude_router

Cpost

Dadd_router

Attempts:

3 left

💡 Hint

Common Mistakes

Using @router.post instead of @router.get for a GET route

Using add_router instead of include_router

Use @router.get to define a GET route and app.include_router to add the router.

5fill in blank

hard

Fill all three blanks to create a router with a prefix and include it in the app.

FastAPI

from fastapi import FastAPI, APIRouter

router = APIRouter(prefix=[1])

@router.get("/")
async def read_items():
    return {"items": []}

app = FastAPI()
app.[2](router, [3]="/items")

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

A"/api"

Binclude_router

Cprefix

D"/items"

Attempts:

3 left

💡 Hint

Common Mistakes

Not using quotes around prefix strings

Using add_router instead of include_router

Confusing prefix argument placement

Set prefix="/api" when creating the router, include it with include_router, and specify prefix="/items" in include_router to override or add prefix.

Practice

1. What is the main purpose of using include_router in a FastAPI application?

easy

A. To handle user authentication automatically.

B. To automatically generate HTML templates for the app.

C. To connect the app to a database.

D. To split the app into smaller, manageable parts for better organization.

Solution

1. Step 1: Understand the role of routers in FastAPI

   Routers help organize routes by grouping related endpoints together.

2. Step 2: Recognize what include_router does

   It adds these grouped routes into the main app, keeping code clean and modular.

3. Final Answer:

   To split the app into smaller, manageable parts for better organization. -> Option D

4. Quick Check:

   Router inclusion = app organization [OK]

Hint: Routers help organize routes; include_router adds them to main app [OK]

Common Mistakes:

• Thinking include_router generates HTML templates
• Confusing routers with database connections
• Assuming include_router handles authentication

2. Which of the following is the correct way to include a router named user_router with prefix /users in a FastAPI app named app?

easy

A. app.add_router(user_router, prefix='/users')

B. app.include_router(user_router, prefix='/users')

C. app.include(user_router, prefix='/users')

D. app.router_include(user_router, prefix='/users')

Solution

1. Step 1: Recall the correct method name for adding routers

   The method is include_router, not add_router or others.

2. Step 2: Check the syntax for prefix argument

   The prefix is passed as a keyword argument prefix='/users'.

3. Final Answer:

   app.include_router(user_router, prefix='/users') -> Option B

4. Quick Check:

   Method name is include_router with prefix argument [OK]

Hint: Use include_router with prefix keyword to add routers [OK]

Common Mistakes:

• Using wrong method names like add_router
• Passing prefix as positional argument
• Misspelling include_router

3. Given this code snippet, what will be the URL path to access the get_items endpoint?

from fastapi import FastAPI, APIRouter

app = FastAPI()
router = APIRouter()

@router.get('/items')
async def get_items():
    return {'items': [1, 2, 3]}

app.include_router(router, prefix='/api')

medium

A. /api/items

B. /items

C. /router/items

D. /api/router/items

Solution

1. Step 1: Identify the route path in the router

   The endpoint is defined at /items inside the router.

2. Step 2: Understand the prefix added when including the router

   The router is included with prefix /api, so the full path is /api/items.

3. Final Answer:

   /api/items -> Option A

4. Quick Check:

   Router prefix + endpoint path = full URL [OK]

Hint: Full path = prefix + router path [OK]

Common Mistakes:

• Ignoring the prefix when accessing the endpoint
• Assuming router name appears in URL
• Confusing endpoint path with prefix

4. What is wrong with this FastAPI code snippet?

from fastapi import FastAPI, APIRouter

app = FastAPI()
router = APIRouter()

@router.get('/hello')
async def say_hello():
    return {'message': 'Hello'}

app.include_router(router, prefix='/greet')
app.include_router(router, prefix='/greet')

medium

A. Including the same router twice with the same prefix causes duplicate routes.

B. The router must be included before defining endpoints.

C. The prefix argument must be omitted when including routers.

D. The router variable should be named app_router instead of router.

Solution

1. Step 1: Check how many times the router is included

   The router is included twice with the same prefix /greet.

2. Step 2: Understand the effect of including the same router twice

   This causes duplicate routes, which can lead to errors or unexpected behavior.

3. Final Answer:

   Including the same router twice with the same prefix causes duplicate routes. -> Option A

4. Quick Check:

   Duplicate router inclusion = duplicate routes [OK]

Hint: Avoid including the same router twice with same prefix [OK]

Common Mistakes:

• Thinking router must be included before endpoints
• Believing prefix is mandatory or must be omitted
• Confusing variable naming with functionality

5. You have two routers: user_router with prefix /users and item_router with prefix /items. You want to include both in your FastAPI app and add tags for automatic docs grouping. Which code snippet correctly includes both routers with tags?

hard

A. app.include_router(user_router, prefix='/users', tags='users')
app.include_router(item_router, prefix='/items', tags='items')

B. app.include_router(user_router, prefix='/users')
app.include_router(item_router, prefix='/items')
app.tags = ['users', 'items']

C. app.include_router(user_router, prefix='/users', tags=['users'])
app.include_router(item_router, prefix='/items', tags=['items'])

D. app.include_router(user_router, tags=['users'])
app.include_router(item_router, tags=['items'])

Solution

1. Step 1: Check how to add tags when including routers

   Tags are passed as a list to the tags argument in include_router.

2. Step 2: Verify prefix and tags usage for both routers

   Each router is included with its prefix and tags as lists, e.g., tags=['users'].

3. Final Answer:

   app.include_router(user_router, prefix='/users', tags=['users']) app.include_router(item_router, prefix='/items', tags=['items']) -> Option C

4. Quick Check:

   Tags must be lists in include_router calls [OK]

Hint: Pass tags as list when including routers for docs grouping [OK]

Common Mistakes:

• Passing tags as string instead of list
• Setting tags on app instead of routers
• Omitting tags argument entirely