Building a JSON CRUD API

Introduction to FastAPI

Matt Eckerle

Software and Data Engineering Leader

Four Steps in Object Management Lifecycle (CRUD)

Create, Read, Update, and Delete around a Database

API Operations

Create

POST operation

Read

GET operation

Update

PUT operation

Delete

DELETE operation

JSON CRUD API Motivation

Fundamentals

Manage the entire object lifecycle
Understand best practices for HTTP API operations
Design our own data management APIs

Opportunities

Business logic for more complex data operations
High throughput data pipelines
Machine Learning inference pipelines

Building a CRUD Module

from pydantic import BaseModel

class Review(BaseModel):
    movie: str
    num_stars: int
    text: str

class DbReview(BaseModel):
    movie: str
    num_stars: int
    text: str
    # Reference database ID of Reviews
    review_id: int

# crud.py
def create_review(review: Review):
    # Create review in database

def read_review(review_id: int):
    # Read review from database

def update_review(review: DbReview):
    # Update review in database

def delete_review(review_id: int):
    # Delete review from database

POST Endpoint to Create

Endpoint: /reviews
Input: Review
Output: DbReview

@app.post("/reviews", response_model=DbReview)
def create_review(review: Review):
    # Create the movie review in the database
    db_review = crud.create_review(review)
    # Return the created review with database ID
    return db_review

GET Endpoint to Read

Endpoint: /reviews
Input: ?review_id=1234
Output: DbReview

@app.get("/reviews", response_model=DbReview)
def read_review(review_id: int):
    # Read the movie review from the database
    db_review = crud.read_review(review_id)
    # Return the review
    return db_review

PUT Endpoint to Update

Endpoint: /reviews
Input: DbReview
Output: DbReview

@app.put("/reviews", response_model=DbReview)
def update_review(review: DbReview):
    # Update the movie review in the database
    db_review = crud.update_review(review)
    # Return the updated review
    return db_review

DELETE Endpoint to Delete

Endpoint: /reviews
Input: DbReview
Output: {}

@app.delete("/reviews")
def delete_review(review: DbReview):
    # Delete the movie review from the database
    crud.delete_review(review.review_id)
    # Return nothing since the data is gone
    return {}

Let's practice!

Introduction to FastAPI