Build simple todo app with FastAPI and SQLite

- Created FastAPI application with CRUD operations for todos
- Implemented SQLite database with SQLAlchemy ORM
- Added Alembic for database migrations
- Set up CORS middleware for all origins
- Added health check endpoint at /health
- Created comprehensive API documentation
- Formatted code with Ruff linter
- Updated README with project information

Features:
- Create, read, update, delete todos
- Pagination support for listing todos
- Auto-generated OpenAPI documentation at /docs
- Health monitoring endpoint

README.md

@@ -1,3 +1,68 @@
-# FastAPI Application
+# Todo App API
 
-This is a FastAPI application bootstrapped by BackendIM, the AI-powered backend generation platform.
+A simple Todo application API built with FastAPI and SQLite.
+
+## Features
+
+- Create, read, update, and delete todos
+- SQLite database with SQLAlchemy ORM
+- Database migrations with Alembic
+- CORS enabled for all origins
+- Health check endpoint
+- Auto-generated API documentation
+
+## Installation
+
+1. Install dependencies:
+```bash
+pip install -r requirements.txt
+```
+
+2. Run the application:
+```bash
+uvicorn main:app --reload
+```
+
+The API will be available at http://localhost:8000
+
+## API Endpoints
+
+- `GET /` - Root endpoint with API information
+- `GET /health` - Health check endpoint
+- `GET /docs` - Interactive API documentation (Swagger UI)
+- `GET /redoc` - Alternative API documentation
+- `POST /todos` - Create a new todo
+- `GET /todos` - Get all todos (with pagination)
+- `GET /todos/{todo_id}` - Get a specific todo
+- `PUT /todos/{todo_id}` - Update a todo
+- `DELETE /todos/{todo_id}` - Delete a todo
+
+## Database
+
+The application uses SQLite database stored at `/app/storage/db/db.sqlite`. Database migrations are managed with Alembic.
+
+## Project Structure
+
+```
+├── main.py                    # FastAPI application entry point
+├── requirements.txt           # Python dependencies
+├── alembic.ini               # Alembic configuration
+├── alembic/                  # Database migrations
+│   ├── env.py
+│   ├── script.py.mako
+│   └── versions/
+│       └── 001_create_todos_table.py
+└── app/
+    ├── __init__.py
+    ├── schemas.py            # Pydantic schemas
+    ├── db/
+    │   ├── __init__.py
+    │   ├── base.py          # SQLAlchemy base
+    │   └── session.py       # Database session
+    ├── models/
+    │   ├── __init__.py
+    │   └── todo.py          # Todo model
+    └── routers/
+        ├── __init__.py
+        └── todos.py         # Todo API endpoints
+```

alembic.ini

@@ -0,0 +1,41 @@
+[alembic]
+script_location = alembic
+prepend_sys_path = .
+version_path_separator = os
+sqlalchemy.url = sqlite:////app/storage/db/db.sqlite
+
+[post_write_hooks]
+
+[loggers]
+keys = root,sqlalchemy,alembic
+
+[handlers]
+keys = console
+
+[formatters]
+keys = generic
+
+[logger_root]
+level = WARN
+handlers = console
+qualname =
+
+[logger_sqlalchemy]
+level = WARN
+handlers =
+qualname = sqlalchemy.engine
+
+[logger_alembic]
+level = INFO
+handlers =
+qualname = alembic
+
+[handler_console]
+class = StreamHandler
+args = (sys.stderr,)
+level = NOTSET
+formatter = generic
+
+[formatter_generic]
+format = %(levelname)-5.5s [%(name)s] %(message)s
+datefmt = %H:%M:%S

alembic/env.py

@@ -0,0 +1,50 @@
+from logging.config import fileConfig
+from sqlalchemy import engine_from_config
+from sqlalchemy import pool
+from alembic import context
+import sys
+import os
+
+sys.path.append(os.path.join(os.path.dirname(__file__), ".."))
+
+from app.db.base import Base
+
+config = context.config
+
+if config.config_file_name is not None:
+    fileConfig(config.config_file_name)
+
+target_metadata = Base.metadata
+
+
+def run_migrations_offline() -> None:
+    url = config.get_main_option("sqlalchemy.url")
+    context.configure(
+        url=url,
+        target_metadata=target_metadata,
+        literal_binds=True,
+        dialect_opts={"paramstyle": "named"},
+    )
+
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+def run_migrations_online() -> None:
+    connectable = engine_from_config(
+        config.get_section(config.config_ini_section),
+        prefix="sqlalchemy.",
+        poolclass=pool.NullPool,
+    )
+
+    with connectable.connect() as connection:
+        context.configure(connection=connection, target_metadata=target_metadata)
+
+        with context.begin_transaction():
+            context.run_migrations()
+
+
+if context.is_offline_mode():
+    run_migrations_offline()
+else:
+    run_migrations_online()

alembic/script.py.mako

@@ -0,0 +1,24 @@
+"""${message}
+
+Revision ID: ${up_revision}
+Revises: ${down_revision | comma,n}
+Create Date: ${create_date}
+
+"""
+from alembic import op
+import sqlalchemy as sa
+${imports if imports else ""}
+
+# revision identifiers, used by Alembic.
+revision = ${repr(up_revision)}
+down_revision = ${repr(down_revision)}
+branch_labels = ${repr(branch_labels)}
+depends_on = ${repr(depends_on)}
+
+
+def upgrade() -> None:
+    ${upgrades if upgrades else "pass"}
+
+
+def downgrade() -> None:
+    ${downgrades if downgrades else "pass"}

alembic/versions/001_create_todos_table.py

@@ -0,0 +1,45 @@
+"""create todos table
+
+Revision ID: 001
+Revises:
+Create Date: 2024-01-01 12:00:00.000000
+
+"""
+
+from alembic import op
+import sqlalchemy as sa
+
+# revision identifiers, used by Alembic.
+revision = "001"
+down_revision = None
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.create_table(
+        "todos",
+        sa.Column("id", sa.Integer(), nullable=False),
+        sa.Column("title", sa.String(), nullable=False),
+        sa.Column("description", sa.String(), nullable=True),
+        sa.Column("completed", sa.Boolean(), nullable=True),
+        sa.Column(
+            "created_at",
+            sa.DateTime(),
+            server_default=sa.text("(CURRENT_TIMESTAMP)"),
+            nullable=True,
+        ),
+        sa.Column(
+            "updated_at",
+            sa.DateTime(),
+            server_default=sa.text("(CURRENT_TIMESTAMP)"),
+            nullable=True,
+        ),
+        sa.PrimaryKeyConstraint("id"),
+    )
+    op.create_index(op.f("ix_todos_id"), "todos", ["id"], unique=False)
+
+
+def downgrade() -> None:
+    op.drop_index(op.f("ix_todos_id"), table_name="todos")
+    op.drop_table("todos")

app/db/base.py

@@ -0,0 +1,3 @@
+from sqlalchemy.ext.declarative import declarative_base
+
+Base = declarative_base()

app/db/session.py

@@ -0,0 +1,22 @@
+from pathlib import Path
+from sqlalchemy import create_engine
+from sqlalchemy.orm import sessionmaker
+
+DB_DIR = Path("/app") / "storage" / "db"
+DB_DIR.mkdir(parents=True, exist_ok=True)
+
+SQLALCHEMY_DATABASE_URL = f"sqlite:///{DB_DIR}/db.sqlite"
+
+engine = create_engine(
+    SQLALCHEMY_DATABASE_URL, connect_args={"check_same_thread": False}
+)
+
+SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
+
+
+def get_db():
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()

app/models/todo.py

@@ -0,0 +1,14 @@
+from sqlalchemy import Column, Integer, String, Boolean, DateTime
+from sqlalchemy.sql import func
+from app.db.base import Base
+
+
+class Todo(Base):
+    __tablename__ = "todos"
+
+    id = Column(Integer, primary_key=True, index=True)
+    title = Column(String, nullable=False)
+    description = Column(String, nullable=True)
+    completed = Column(Boolean, default=False)
+    created_at = Column(DateTime, server_default=func.now())
+    updated_at = Column(DateTime, server_default=func.now(), onupdate=func.now())

app/routers/todos.py

@@ -0,0 +1,57 @@
+from fastapi import APIRouter, Depends, HTTPException
+from sqlalchemy.orm import Session
+from typing import List
+from app.db.session import get_db
+from app.models.todo import Todo
+from app.schemas import TodoCreate, TodoUpdate, TodoResponse
+
+router = APIRouter(prefix="/todos", tags=["todos"])
+
+
+@router.post("/", response_model=TodoResponse)
+def create_todo(todo: TodoCreate, db: Session = Depends(get_db)):
+    db_todo = Todo(**todo.dict())
+    db.add(db_todo)
+    db.commit()
+    db.refresh(db_todo)
+    return db_todo
+
+
+@router.get("/", response_model=List[TodoResponse])
+def get_todos(skip: int = 0, limit: int = 100, db: Session = Depends(get_db)):
+    todos = db.query(Todo).offset(skip).limit(limit).all()
+    return todos
+
+
+@router.get("/{todo_id}", response_model=TodoResponse)
+def get_todo(todo_id: int, db: Session = Depends(get_db)):
+    todo = db.query(Todo).filter(Todo.id == todo_id).first()
+    if todo is None:
+        raise HTTPException(status_code=404, detail="Todo not found")
+    return todo
+
+
+@router.put("/{todo_id}", response_model=TodoResponse)
+def update_todo(todo_id: int, todo_update: TodoUpdate, db: Session = Depends(get_db)):
+    todo = db.query(Todo).filter(Todo.id == todo_id).first()
+    if todo is None:
+        raise HTTPException(status_code=404, detail="Todo not found")
+
+    update_data = todo_update.dict(exclude_unset=True)
+    for field, value in update_data.items():
+        setattr(todo, field, value)
+
+    db.commit()
+    db.refresh(todo)
+    return todo
+
+
+@router.delete("/{todo_id}")
+def delete_todo(todo_id: int, db: Session = Depends(get_db)):
+    todo = db.query(Todo).filter(Todo.id == todo_id).first()
+    if todo is None:
+        raise HTTPException(status_code=404, detail="Todo not found")
+
+    db.delete(todo)
+    db.commit()
+    return {"message": "Todo deleted successfully"}

app/schemas.py

@@ -0,0 +1,28 @@
+from pydantic import BaseModel
+from typing import Optional
+from datetime import datetime
+
+
+class TodoBase(BaseModel):
+    title: str
+    description: Optional[str] = None
+    completed: bool = False
+
+
+class TodoCreate(TodoBase):
+    pass
+
+
+class TodoUpdate(BaseModel):
+    title: Optional[str] = None
+    description: Optional[str] = None
+    completed: Optional[bool] = None
+
+
+class TodoResponse(TodoBase):
+    id: int
+    created_at: datetime
+    updated_at: datetime
+
+    class Config:
+        from_attributes = True

main.py

@@ -0,0 +1,39 @@
+from fastapi import FastAPI
+from fastapi.middleware.cors import CORSMiddleware
+from app.routers import todos
+from app.db.session import engine
+from app.db.base import Base
+
+Base.metadata.create_all(bind=engine)
+
+app = FastAPI(
+    title="Todo App API",
+    description="A simple Todo application API built with FastAPI",
+    version="1.0.0",
+    openapi_url="/openapi.json",
+)
+
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=["*"],
+    allow_credentials=True,
+    allow_methods=["*"],
+    allow_headers=["*"],
+)
+
+app.include_router(todos.router)
+
+
+@app.get("/")
+def read_root():
+    return {
+        "title": "Todo App API",
+        "description": "A simple Todo application API built with FastAPI",
+        "documentation": "/docs",
+        "health_check": "/health",
+    }
+
+
+@app.get("/health")
+def health_check():
+    return {"status": "healthy", "service": "todo-api"}

requirements.txt

@@ -0,0 +1,7 @@
+fastapi==0.104.1
+uvicorn==0.24.0
+sqlalchemy==2.0.23
+alembic==1.12.1
+python-multipart==0.0.6
+pydantic==2.5.0
+ruff==0.1.6