CRUD Operations with SQLAlchemy

Welcome to Lesson 3! Today, we'll master CRUD operations using FastAPI and SQLAlchemy. CRUD stands for:

• Create: Adding new data.
• Read: Retrieving existing data.
• Update: Modifying existing data.
• Delete: Removing data.

These four operations are the foundation of almost any application that interacts with a database.

Before diving into CRUD, let's set up our SQLAlchemy model and Pydantic schemas. We'll use an in-memory SQLite database for our runnable examples.

First, our SQLAlchemy Todo model to represent a task:

from sqlalchemy import Column, Integer, String, Boolean
from sqlalchemy.ext.declarative import declarative_base

Base = declarative_base()

class Todo(Base):
    __tablename__ = "todos"
    id = Column(Integer, primary_key=True, index=True)
    title = Column(String, index=True)
    description = Column(String, default="")
    completed = Column(Boolean, default=False)

And Pydantic schemas for request/response:

from pydantic import BaseModel

class TodoCreate(BaseModel):
    title: str
    description: str = ""
    completed: bool = False

class TodoResponse(TodoCreate):
    id: int

    class Config:
        orm_mode = True