Multiple path parameters in FastAPI - Mini Project: Build & Apply

Body with multiple parameters in FastAPI

📖 Scenario: You are building a simple API to receive user information and preferences in one request.

🎯 Goal: Create a FastAPI endpoint that accepts multiple parameters in the request body using Pydantic models.

📋 What You'll Learn

Create two Pydantic models: User and Preferences with specified fields

Create a FastAPI app instance called app

Create a POST endpoint /submit that accepts user and preferences as body parameters

Return a dictionary combining data from both models

💡 Why This Matters

🌍 Real World

APIs often need to accept complex data with multiple parts in one request, like user info and settings.

💼 Career

Understanding how to handle multiple body parameters is essential for backend developers working with FastAPI to build flexible APIs.

1

Create Pydantic models for user and preferences

Create a Pydantic model called User with fields name (str) and age (int). Also create a Pydantic model called Preferences with fields newsletter (bool) and notifications (bool).

FastAPI

# Create User and Preferences Pydantic models here
from pydantic import BaseModel

# Your code here

Need a hint?

Use class User(BaseModel): and define the fields with types inside.

2

Create FastAPI app instance

Create a FastAPI app instance called app.

FastAPI

from fastapi import FastAPI
from pydantic import BaseModel

class User(BaseModel):
    name: str
    age: int

class Preferences(BaseModel):
    newsletter: bool
    notifications: bool

# Create FastAPI app instance
# Your code here

Need a hint?

Use app = FastAPI() to create the app instance.

3

Create POST endpoint with multiple body parameters

Create a POST endpoint /submit using @app.post decorator. Define a function submit that accepts two parameters: user of type User and preferences of type Preferences. Both should come from the request body.

FastAPI

from fastapi import FastAPI
from pydantic import BaseModel

class User(BaseModel):
    name: str
    age: int

class Preferences(BaseModel):
    newsletter: bool
    notifications: bool

app = FastAPI()

# Create POST endpoint /submit with user and preferences body parameters
# Your code here

Need a hint?

Use @app.post("/submit") and define the function with parameters typed as User and Preferences.

4

Add Body import and use Body() for multiple parameters

Import Body from fastapi. Update the submit function parameters to use Body(...) for both user and preferences to explicitly declare them as body parameters.

FastAPI

from fastapi import FastAPI, Body
from pydantic import BaseModel

class User(BaseModel):
    name: str
    age: int

class Preferences(BaseModel):
    newsletter: bool
    notifications: bool

app = FastAPI()

@app.post("/submit")
async def submit(user: User = Body(...), preferences: Preferences = Body(...)):
    return {"user": user, "preferences": preferences}

# Your code here

Need a hint?

Use from fastapi import Body and set parameters like user: User = Body(...).