FastAPI integration patterns in LangChain - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

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

LangChain

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

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AResponse

BRequest

CFastAPI

DDepends

Attempts:

3 left

💡 Hint

Common Mistakes

Importing Request or Response instead of FastAPI

Not creating an instance of FastAPI

You need to import FastAPI and create an instance of it to start your app.

2fill in blank

medium

Complete the code to define a GET endpoint that returns a greeting.

LangChain

@app.[1]("/")
async def read_root():
    return {"message": "Hello World"}

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Apost

Bdelete

Cput

Dget

Attempts:

3 left

💡 Hint

Common Mistakes

Using POST or PUT instead of GET for a read endpoint

Forgetting the decorator

The decorator @app.get defines a GET HTTP method endpoint.

3fill in blank

hard

Fix the error in the code to correctly inject a dependency using Depends.

LangChain

from fastapi import Depends

def get_token():
    return "token123"

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

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ADependsWith

BDepends

CDependsOn

DRequest

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect names like DependsOn or DependsWith

Not importing Depends

Use Depends to declare dependencies in FastAPI endpoints.

4fill in blank

hard

Fill both blanks to create a POST endpoint that accepts a Pydantic model and returns it.

LangChain

from pydantic import BaseModel

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

@app.[1]("/items")
async def create_item(item: [2]):
    return item

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Apost

BItem

Cget

Dstr

Attempts:

3 left

💡 Hint

Common Mistakes

Using GET instead of POST for creation

Using wrong parameter type like str

Use @app.post to define a POST endpoint and use the Pydantic model Item as the parameter type.

5fill in blank

hard

Fill all three blanks to create a FastAPI app with a startup event and a simple GET endpoint.

LangChain

from fastapi import [1]

app = [2]()

@app.[3]("/status")
async def status():
    return {"status": "ok"}

@app.on_event("startup")
async def startup_event():
    print("App is starting")

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AFastAPI

Cget

DDepends

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong import or instance name

Using wrong decorator for the endpoint

Import FastAPI, create an app instance, and define a GET endpoint with @app.get.