POST operations

Introduction to FastAPI

Matt Eckerle

Software and Data Engineering Leader

GET vs. POST Operations

GET Operations

Traditional use: request info about an object
Parameters sent via query string
Can be sent from a web browser

api = "http://moviereviews.co/reviews/1"
response = requests.get(api)

POST Operations

Traditional use: create a new object
Parameters sent via query string as well as request body
Requires an application or framework
- e.g. cURL, requests

api = "http://moviereviews.co/reviews/"
body = {"text": "A great movie!"}
response = requests.post(api, json=body)

HTTP Request Body

Data sent after the HTTP request header
Header specifies body encoding
Supports nested data structures
JSON and XML are the most common encodings for APIs
JSON is FastAPI default encoding

JSON Example

# Create a record for a movie review
{"movie": "The Neverending Story",
 "review": {"num_stars": 4,
            "text": "Great movie!",
            "public": true}}

Using pydantic's BaseModel

pydantic: interface to define request and response body schemas

Note

We are nesting Review inside MovieReview

from pydantic import BaseModel

class Review(BaseModel):
    num_stars: int
    text: str
    public: bool = False

class MovieReview(BaseModel):
    movie: str
    # Nest Review in MovieReview
    review: Review

Handling a POST Operation

POST endpoint to create a new movie review:

Endpoint: /reviews
Input: MovieReview (from previous slide)
Output: db_review (defined elsewhere)

@app.post("/reviews", response_model=DbReview)
def create_review(review: MovieReview):
    # Persist the movie review to the database
    db_review = crud.create_review(review)
    # Return the review including database ID
    return db_review

¹ https://fastapi.tiangolo.com/tutorial/sql-databases/#crud-utils

Let's practice!

Introduction to FastAPI