Add simple todo app using FastAPI and SQLite

- Implement Todo database model with SQLAlchemy
- Set up Alembic for database migrations
- Create CRUD operations for Todo items
- Implement RESTful API endpoints
- Add health check endpoint
- Include comprehensive README with usage instructions

README.md

@@ -1,3 +1,108 @@
-# FastAPI Application
+# Simple Todo App
 
-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 Todo items
+- SQLite database with SQLAlchemy ORM
+- Alembic migrations for database versioning
+- API documentation with Swagger UI
+- Health check endpoint
+
+## Requirements
+
+- Python 3.7+
+- FastAPI
+- SQLAlchemy
+- Alembic
+- Uvicorn
+- Ruff (for linting)
+
+## Installation
+
+1. Clone the repository:
+
+```bash
+git clone https://github.com/yourusername/simpletodoapp.git
+cd simpletodoapp
+```
+
+2. Install dependencies:
+
+```bash
+pip install -r requirements.txt
+```
+
+3. Run migrations:
+
+```bash
+alembic upgrade head
+```
+
+## Running the Application
+
+Start the application with:
+
+```bash
+uvicorn main:app --reload
+```
+
+The API will be available at http://localhost:8000
+
+## API Documentation
+
+Once the application is running, you can access the interactive API documentation at:
+
+- Swagger UI: http://localhost:8000/docs
+- ReDoc: http://localhost:8000/redoc
+
+## API Endpoints
+
+### Todo Endpoints
+
+- `GET /api/todos` - Get all todos
+- `POST /api/todos` - Create a new todo
+- `GET /api/todos/{todo_id}` - Get a specific todo
+- `PATCH /api/todos/{todo_id}` - Update a todo
+- `DELETE /api/todos/{todo_id}` - Delete a todo
+
+### Health Check
+
+- `GET /health` - Check API health status
+
+## Database
+
+The application uses SQLite as the database with SQLAlchemy as the ORM. The database file is stored at `/app/storage/db/db.sqlite`.
+
+## Development
+
+### Linting
+
+```bash
+ruff check .
+ruff check --fix .
+```
+
+### Running Tests
+
+```bash
+# No tests implemented yet
+```
+
+## Project Structure
+
+```
+simpletodoapp/
+├── app/
+│   ├── crud/       # CRUD operations
+│   ├── models/     # SQLAlchemy models
+│   ├── routers/    # API endpoints
+│   ├── schemas/    # Pydantic schemas
+│   └── database.py # Database configuration
+├── migrations/     # Alembic migrations
+├── main.py         # Application entry point
+├── alembic.ini     # Alembic configuration
+├── requirements.txt # Dependencies
+└── README.md       # Project documentation
+```

alembic.ini

@@ -0,0 +1,85 @@
+# A generic, single database configuration.
+
+[alembic]
+# path to migration scripts
+script_location = migrations
+
+# template used to generate migration files
+# file_template = %%(rev)s_%%(slug)s
+
+# timezone to use when rendering the date
+# within the migration file as well as the filename.
+# string value is passed to dateutil.tz.gettz()
+# leave blank for localtime
+# timezone =
+
+# max length of characters to apply to the
+# "slug" field
+# truncate_slug_length = 40
+
+# set to 'true' to run the environment during
+# the 'revision' command, regardless of autogenerate
+# revision_environment = false
+
+# set to 'true' to allow .pyc and .pyo files without
+# a source .py file to be detected as revisions in the
+# versions/ directory
+# sourceless = false
+
+# version location specification; this defaults
+# to migrations/versions.  When using multiple version
+# directories, initial revisions must be specified with --version-path
+# version_locations = %(here)s/bar %(here)s/bat migrations/versions
+
+# the output encoding used when revision files
+# are written from script.py.mako
+# output_encoding = utf-8
+
+# SQLite database URL (using absolute path)
+sqlalchemy.url = sqlite:////app/storage/db/db.sqlite
+
+[post_write_hooks]
+# post_write_hooks defines scripts or Python functions that are run
+# on newly generated revision scripts.  See the documentation for further
+# detail and examples
+
+# format using "black" - use the console_scripts runner, against the "black" entrypoint
+# hooks=black
+# black.type=console_scripts
+# black.entrypoint=black
+# black.options=-l 79
+
+# Logging configuration
+[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

app/crud/__init__.py

@@ -0,0 +1,9 @@
+from app.crud.todo import (
+    create_todo,
+    get_todo,
+    get_todos,
+    update_todo,
+    delete_todo,
+)
+
+__all__ = ["create_todo", "get_todo", "get_todos", "update_todo", "delete_todo"]

app/crud/todo.py

@@ -0,0 +1,97 @@
+from typing import List, Optional
+from sqlalchemy.orm import Session
+from app.models.todo import Todo
+from app.schemas.todo import TodoCreate, TodoUpdate
+
+
+def get_todo(db: Session, todo_id: int) -> Optional[Todo]:
+    """
+    Get a single todo item by ID.
+    
+    Args:
+        db: Database session
+        todo_id: ID of the todo to retrieve
+        
+    Returns:
+        Todo object if found, None otherwise
+    """
+    return db.query(Todo).filter(Todo.id == todo_id).first()
+
+
+def get_todos(db: Session, skip: int = 0, limit: int = 100) -> List[Todo]:
+    """
+    Get multiple todo items with pagination.
+    
+    Args:
+        db: Database session
+        skip: Number of records to skip
+        limit: Maximum number of records to return
+        
+    Returns:
+        List of Todo objects
+    """
+    return db.query(Todo).order_by(Todo.created_at.desc()).offset(skip).limit(limit).all()
+
+
+def create_todo(db: Session, todo: TodoCreate) -> Todo:
+    """
+    Create a new todo item.
+    
+    Args:
+        db: Database session
+        todo: TodoCreate schema with new todo data
+        
+    Returns:
+        Created Todo object
+    """
+    db_todo = Todo(**todo.model_dump())
+    db.add(db_todo)
+    db.commit()
+    db.refresh(db_todo)
+    return db_todo
+
+
+def update_todo(db: Session, todo_id: int, todo: TodoUpdate) -> Optional[Todo]:
+    """
+    Update an existing todo item.
+    
+    Args:
+        db: Database session
+        todo_id: ID of the todo to update
+        todo: TodoUpdate schema with fields to update
+        
+    Returns:
+        Updated Todo object if found, None otherwise
+    """
+    db_todo = db.query(Todo).filter(Todo.id == todo_id).first()
+    if db_todo is None:
+        return None
+    
+    # Update only provided fields
+    todo_data = todo.model_dump(exclude_unset=True)
+    for key, value in todo_data.items():
+        setattr(db_todo, key, value)
+    
+    db.commit()
+    db.refresh(db_todo)
+    return db_todo
+
+
+def delete_todo(db: Session, todo_id: int) -> bool:
+    """
+    Delete a todo item.
+    
+    Args:
+        db: Database session
+        todo_id: ID of the todo to delete
+        
+    Returns:
+        True if deleted, False if not found
+    """
+    db_todo = db.query(Todo).filter(Todo.id == todo_id).first()
+    if db_todo is None:
+        return False
+    
+    db.delete(db_todo)
+    db.commit()
+    return True

app/database.py

@@ -0,0 +1,35 @@
+from pathlib import Path
+from sqlalchemy import create_engine
+from sqlalchemy.orm import sessionmaker, declarative_base
+from sqlalchemy.ext.declarative import DeclarativeMeta
+
+# Create database directory
+DB_DIR = Path("/app") / "storage" / "db"
+DB_DIR.mkdir(parents=True, exist_ok=True)
+
+# SQLite database URL
+SQLALCHEMY_DATABASE_URL = f"sqlite:///{DB_DIR}/db.sqlite"
+
+# Create SQLAlchemy engine with SQLite-specific connection arguments
+engine = create_engine(
+    SQLALCHEMY_DATABASE_URL,
+    connect_args={"check_same_thread": False}
+)
+
+# Create a SessionLocal class
+SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
+
+# Create a Base class for declarative models
+Base: DeclarativeMeta = declarative_base()
+
+def init_db() -> None:
+    """Initialize database by creating all tables."""
+    Base.metadata.create_all(bind=engine)
+
+def get_db():
+    """Dependency function for getting database session."""
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()

app/models/__init__.py

@@ -0,0 +1,3 @@
+from app.models.todo import Todo
+
+__all__ = ["Todo"]

app/models/todo.py

@@ -0,0 +1,16 @@
+from sqlalchemy import Column, Integer, String, Boolean, DateTime
+from sqlalchemy.sql import func
+from app.database import Base
+
+
+class Todo(Base):
+    """SQLAlchemy model for Todo items."""
+    
+    __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(timezone=True), server_default=func.now())
+    updated_at = Column(DateTime(timezone=True), server_default=func.now(), onupdate=func.now())

app/routers/health.py

@@ -0,0 +1,37 @@
+from fastapi import APIRouter, Depends
+from sqlalchemy.orm import Session
+from sqlalchemy import text
+from pydantic import BaseModel
+
+from app.database import get_db
+
+router = APIRouter()
+
+
+class HealthResponse(BaseModel):
+    """Response model for health check endpoint."""
+    
+    status: str
+    version: str
+    database: str
+
+
+@router.get("/health", response_model=HealthResponse)
+def health_check(db: Session = Depends(get_db)) -> HealthResponse:
+    """
+    Health check endpoint to verify API and database status.
+    
+    Args:
+        db: Database session
+        
+    Returns:
+        Health status information
+    """
+    # Test database connectivity
+    db.execute(text("SELECT 1"))
+    
+    return HealthResponse(
+        status="healthy",
+        version="0.1.0",
+        database="connected"
+    )

app/routers/todos.py

@@ -0,0 +1,115 @@
+from typing import List
+from fastapi import APIRouter, Depends, HTTPException, status, Query
+from sqlalchemy.orm import Session
+
+from app.database import get_db
+from app.models.todo import Todo
+from app.schemas.todo import TodoCreate, TodoRead, TodoUpdate
+from app.crud.todo import create_todo, get_todo, get_todos, update_todo, delete_todo
+
+router = APIRouter()
+
+
+@router.post("/todos", response_model=TodoRead, status_code=status.HTTP_201_CREATED)
+def create_todo_api(todo: TodoCreate, db: Session = Depends(get_db)) -> Todo:
+    """
+    Create a new todo item.
+    
+    Args:
+        todo: Todo item data
+        db: Database session
+        
+    Returns:
+        Created todo item
+    """
+    return create_todo(db=db, todo=todo)
+
+
+@router.get("/todos", response_model=List[TodoRead])
+def read_todos(
+    skip: int = Query(0, ge=0, description="Number of todos to skip"),
+    limit: int = Query(100, ge=1, le=100, description="Maximum number of todos to return"),
+    db: Session = Depends(get_db)
+) -> List[Todo]:
+    """
+    Get all todo items with pagination.
+    
+    Args:
+        skip: Number of records to skip
+        limit: Maximum number of records to return
+        db: Database session
+        
+    Returns:
+        List of todo items
+    """
+    return get_todos(db=db, skip=skip, limit=limit)
+
+
+@router.get("/todos/{todo_id}", response_model=TodoRead)
+def read_todo(todo_id: int, db: Session = Depends(get_db)) -> Todo:
+    """
+    Get a specific todo item by ID.
+    
+    Args:
+        todo_id: ID of the todo to retrieve
+        db: Database session
+        
+    Returns:
+        Todo item if found
+        
+    Raises:
+        HTTPException: If todo is not found
+    """
+    db_todo = get_todo(db=db, todo_id=todo_id)
+    if db_todo is None:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail=f"Todo with ID {todo_id} not found"
+        )
+    return db_todo
+
+
+@router.patch("/todos/{todo_id}", response_model=TodoRead)
+def update_todo_api(todo_id: int, todo: TodoUpdate, db: Session = Depends(get_db)) -> Todo:
+    """
+    Update a todo item.
+    
+    Args:
+        todo_id: ID of the todo to update
+        todo: Updated todo data
+        db: Database session
+        
+    Returns:
+        Updated todo item
+        
+    Raises:
+        HTTPException: If todo is not found
+    """
+    db_todo = update_todo(db=db, todo_id=todo_id, todo=todo)
+    if db_todo is None:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail=f"Todo with ID {todo_id} not found"
+        )
+    return db_todo
+
+
+@router.delete("/todos/{todo_id}", status_code=status.HTTP_204_NO_CONTENT, response_model=None)
+def delete_todo_api(todo_id: int, db: Session = Depends(get_db)) -> None:
+    """
+    Delete a todo item.
+    
+    Args:
+        todo_id: ID of the todo to delete
+        db: Database session
+        
+    Raises:
+        HTTPException: If todo is not found
+    """
+    success = delete_todo(db=db, todo_id=todo_id)
+    if not success:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail=f"Todo with ID {todo_id} not found"
+        )
+    return None

app/schemas/__init__.py

@@ -0,0 +1,3 @@
+from app.schemas.todo import TodoCreate, TodoRead, TodoUpdate
+
+__all__ = ["TodoCreate", "TodoRead", "TodoUpdate"]

app/schemas/todo.py

@@ -0,0 +1,38 @@
+from pydantic import BaseModel, Field
+from typing import Optional
+from datetime import datetime
+
+
+class TodoBase(BaseModel):
+    """Base Pydantic schema for Todo items."""
+    
+    title: str = Field(..., min_length=1, max_length=100, description="Title of the todo item")
+    description: Optional[str] = Field(None, max_length=500, description="Optional description of the todo item")
+
+
+class TodoCreate(TodoBase):
+    """Pydantic schema for creating Todo items."""
+    
+    pass
+
+
+class TodoUpdate(BaseModel):
+    """Pydantic schema for updating Todo items."""
+    
+    title: Optional[str] = Field(None, min_length=1, max_length=100, description="Title of the todo item")
+    description: Optional[str] = Field(None, max_length=500, description="Description of the todo item")
+    completed: Optional[bool] = Field(None, description="Whether the todo is completed")
+
+
+class TodoRead(TodoBase):
+    """Pydantic schema for reading Todo items."""
+    
+    id: int
+    completed: bool
+    created_at: datetime
+    updated_at: datetime
+    
+    class Config:
+        """Pydantic config for TodoRead."""
+        
+        from_attributes = True

main.py

@@ -0,0 +1,36 @@
+from fastapi import FastAPI
+from fastapi.middleware.cors import CORSMiddleware
+from contextlib import asynccontextmanager
+
+from app.database import init_db
+from app.routers import todos, health
+
+@asynccontextmanager
+async def lifespan(app: FastAPI):
+    # Initialize database
+    init_db()
+    yield
+
+app = FastAPI(
+    title="SimpleTodoApp",
+    description="A simple Todo application API built with FastAPI",
+    version="0.1.0",
+    lifespan=lifespan,
+)
+
+# Add CORS middleware
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=["*"],
+    allow_credentials=True,
+    allow_methods=["*"],
+    allow_headers=["*"],
+)
+
+# Include routers
+app.include_router(todos.router, prefix="/api", tags=["todos"])
+app.include_router(health.router, tags=["health"])
+
+if __name__ == "__main__":
+    import uvicorn
+    uvicorn.run("main:app", host="0.0.0.0", port=8000, reload=True)

migrations/README

@@ -0,0 +1 @@
+Generic single-database configuration with Alembic.

migrations/env.py

@@ -0,0 +1,80 @@
+from logging.config import fileConfig
+
+from sqlalchemy import engine_from_config
+from sqlalchemy import pool
+
+from alembic import context
+from app.database import Base
+
+# this is the Alembic Config object, which provides
+# access to the values within the .ini file in use.
+config = context.config
+
+# Interpret the config file for Python logging.
+# This line sets up loggers basically.
+fileConfig(config.config_file_name)
+
+# add your model's MetaData object here
+# for 'autogenerate' support
+target_metadata = Base.metadata
+
+# other values from the config, defined by the needs of env.py,
+# can be acquired:
+# my_important_option = config.get_main_option("my_important_option")
+# ... etc.
+
+
+def run_migrations_offline():
+    """Run migrations in 'offline' mode.
+
+    This configures the context with just a URL
+    and not an Engine, though an Engine is acceptable
+    here as well.  By skipping the Engine creation
+    we don't even need a DBAPI to be available.
+
+    Calls to context.execute() here emit the given string to the
+    script output.
+
+    """
+    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():
+    """Run migrations in 'online' mode.
+
+    In this scenario we need to create an Engine
+    and associate a connection with the context.
+
+    """
+    connectable = engine_from_config(
+        config.get_section(config.config_ini_section),
+        prefix="sqlalchemy.",
+        poolclass=pool.NullPool,
+    )
+
+    with connectable.connect() as connection:
+        is_sqlite = connection.dialect.name == 'sqlite'
+        context.configure(
+            connection=connection,
+            target_metadata=target_metadata,
+            render_as_batch=is_sqlite,  # Key configuration for SQLite
+            compare_type=True
+        )
+
+        with context.begin_transaction():
+            context.run_migrations()
+
+
+if context.is_offline_mode():
+    run_migrations_offline()
+else:
+    run_migrations_online()

migrations/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():
+    ${upgrades if upgrades else "pass"}
+
+
+def downgrade():
+    ${downgrades if downgrades else "pass"}

migrations/versions/7f2e5d33a8bc_create_todos_table.py

@@ -0,0 +1,35 @@
+"""create_todos_table
+
+Revision ID: 7f2e5d33a8bc
+Revises: 
+Create Date: 2023-11-27 00:00:00.000000
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = '7f2e5d33a8bc'
+down_revision = None
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    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, default=False),
+        sa.Column('created_at', sa.DateTime(timezone=True), server_default=sa.text('(CURRENT_TIMESTAMP)'), nullable=True),
+        sa.Column('updated_at', sa.DateTime(timezone=True), 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():
+    op.drop_index(op.f('ix_todos_id'), table_name='todos')
+    op.drop_table('todos')

requirements.txt

@@ -0,0 +1,6 @@
+fastapi>=0.104.1
+uvicorn>=0.24.0
+pydantic>=2.4.2
+sqlalchemy>=2.0.23
+alembic>=1.12.1
+ruff>=0.1.6