Initial Todo app backend implementation with FastAPI and SQLite

- Created FastAPI application structure
- Added Todo model and CRUD operations
- Added database integration with SQLAlchemy
- Added migrations with Alembic
- Added health endpoint
- Added API documentation with Swagger UI and ReDoc

.gitignore

@@ -0,0 +1,43 @@
+# Python
+__pycache__/
+*.py[cod]
+*$py.class
+*.so
+.Python
+build/
+develop-eggs/
+dist/
+downloads/
+eggs/
+.eggs/
+lib/
+lib64/
+parts/
+sdist/
+var/
+wheels/
+*.egg-info/
+.installed.cfg
+*.egg
+
+# Virtual environment
+venv/
+env/
+ENV/
+
+# IDE
+.idea/
+.vscode/
+*.swp
+*.swo
+
+# SQLite
+*.sqlite
+*.db
+
+# Logs
+*.log
+
+# Local environment variables
+.env
+.env.local

README.md

@@ -1,3 +1,55 @@
-# FastAPI Application
+# SimpleTodoApp API
 
-This is a FastAPI application bootstrapped by BackendIM, the AI-powered backend generation platform.
+A FastAPI-based backend for a simple Todo application with SQLite database.
+
+## Features
+
+- Create, read, update, and delete Todo items
+- Health check endpoint
+- SQLite database with SQLAlchemy ORM
+- Database migrations with Alembic
+- Comprehensive API documentation with Swagger UI and ReDoc
+
+## Project Structure
+
+```
+simpletodoapp/
+├── api/                  # API-related code
+│   ├── crud/             # CRUD operations
+│   ├── routers/          # API endpoints
+│   └── schemas/          # Pydantic models for request/response validation
+├── db/                   # Database-related code
+│   ├── database.py       # Database connection and session
+│   └── models.py         # SQLAlchemy models
+├── migrations/           # Alembic migrations
+├── alembic.ini           # Alembic configuration
+├── main.py               # FastAPI application entry point
+└── requirements.txt      # Project dependencies
+```
+
+## Installation & Setup
+
+1. Clone this repository
+2. Install dependencies:
+   ```
+   pip install -r requirements.txt
+   ```
+3. Run the application:
+   ```
+   uvicorn main:app --reload
+   ```
+
+## API Documentation
+
+Once the server is running, you can access:
+- Swagger UI documentation at `/docs`
+- ReDoc documentation at `/redoc`
+
+## API Endpoints
+
+- `GET /health` - Health check endpoint
+- `GET /api/todos` - List all todos
+- `GET /api/todos/{id}` - Get a single todo by ID
+- `POST /api/todos` - Create a new todo
+- `PATCH /api/todos/{id}` - Update a todo (partial update)
+- `DELETE /api/todos/{id}` - Delete a todo

alembic.ini

@@ -0,0 +1,82 @@
+# 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
+
+# sys.path path, will be prepended to sys.path if present.
+# defaults to the current working directory.
+prepend_sys_path = .
+
+# timezone to use when rendering the date within the migration file
+# as well as the filename.
+# If specified, requires the python-dateutil library that can be
+# installed by adding `alembic[tz]` to the pip requirements
+# 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
+
+# SQLite with 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 REVISION_SCRIPT_FILENAME
+
+# 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

api/__init__.py

@@ -0,0 +1 @@
+# This file makes the api directory a Python package

api/crud/__init__.py

@@ -0,0 +1 @@
+# This file makes the crud directory a Python package

api/crud/todo.py

@@ -0,0 +1,61 @@
+from sqlalchemy.orm import Session
+from typing import List, Optional
+from db.models import Todo
+from api.schemas.todo import TodoCreate, TodoUpdate
+
+
+def get_todos(db: Session, skip: int = 0, limit: int = 100) -> List[Todo]:
+    """
+    Get all todos with pagination
+    """
+    return db.query(Todo).offset(skip).limit(limit).all()
+
+
+def get_todo(db: Session, todo_id: int) -> Optional[Todo]:
+    """
+    Get a specific todo by ID
+    """
+    return db.query(Todo).filter(Todo.id == todo_id).first()
+
+
+def create_todo(db: Session, todo: TodoCreate) -> Todo:
+    """
+    Create a new todo
+    """
+    db_todo = Todo(**todo.dict())
+    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
+    """
+    db_todo = get_todo(db, todo_id)
+    if db_todo is None:
+        return None
+    
+    # Update only provided fields
+    todo_data = todo.dict(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 by ID
+    Returns True if the todo was deleted, False if it didn't exist
+    """
+    db_todo = get_todo(db, todo_id)
+    if db_todo is None:
+        return False
+    
+    db.delete(db_todo)
+    db.commit()
+    return True

api/routers/__init__.py

@@ -0,0 +1 @@
+# This file makes the routers directory a Python package

api/routers/health_router.py

@@ -0,0 +1,34 @@
+from fastapi import APIRouter, Depends
+from sqlalchemy.orm import Session
+import platform
+import sys
+
+from db.database import get_db
+from api.schemas.health import HealthResponse
+
+router = APIRouter()
+
+
+@router.get("/health", response_model=HealthResponse)
+def health_check(db: Session = Depends(get_db)):
+    """
+    Health check endpoint that verifies the API is running correctly
+    and can connect to the database
+    """
+    # Verify database connection
+    try:
+        # Just run a simple query to verify DB connection
+        db.execute("SELECT 1")
+        db_status = "healthy"
+    except Exception as e:
+        db_status = f"unhealthy: {str(e)}"
+
+    return HealthResponse(
+        status="healthy",
+        version="0.1.0",
+        details={
+            "database": db_status,
+            "python_version": sys.version,
+            "platform": platform.platform(),
+        }
+    )

api/routers/todo_router.py

@@ -0,0 +1,59 @@
+from fastapi import APIRouter, Depends, HTTPException, status
+from sqlalchemy.orm import Session
+from typing import List
+
+from db.database import get_db
+from api.schemas.todo import TodoCreate, TodoResponse, TodoUpdate
+from api.crud.todo import get_todos, get_todo, create_todo, update_todo, delete_todo
+
+router = APIRouter()
+
+
+@router.get("/", response_model=List[TodoResponse])
+def read_todos(skip: int = 0, limit: int = 100, db: Session = Depends(get_db)):
+    """
+    Get all todos with pagination
+    """
+    todos = get_todos(db, skip=skip, limit=limit)
+    return todos
+
+
+@router.get("/{todo_id}", response_model=TodoResponse)
+def read_todo(todo_id: int, db: Session = Depends(get_db)):
+    """
+    Get a specific todo by ID
+    """
+    db_todo = get_todo(db, todo_id=todo_id)
+    if db_todo is None:
+        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Todo not found")
+    return db_todo
+
+
+@router.post("/", response_model=TodoResponse, status_code=status.HTTP_201_CREATED)
+def create_new_todo(todo: TodoCreate, db: Session = Depends(get_db)):
+    """
+    Create a new todo
+    """
+    return create_todo(db=db, todo=todo)
+
+
+@router.patch("/{todo_id}", response_model=TodoResponse)
+def update_existing_todo(todo_id: int, todo: TodoUpdate, db: Session = Depends(get_db)):
+    """
+    Update an existing todo (partial update)
+    """
+    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="Todo not found")
+    return db_todo
+
+
+@router.delete("/{todo_id}", status_code=status.HTTP_204_NO_CONTENT)
+def delete_existing_todo(todo_id: int, db: Session = Depends(get_db)):
+    """
+    Delete a todo
+    """
+    success = delete_todo(db=db, todo_id=todo_id)
+    if not success:
+        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Todo not found")
+    return None

api/schemas/__init__.py

@@ -0,0 +1 @@
+# This file makes the schemas directory a Python package

api/schemas/health.py

@@ -0,0 +1,9 @@
+from pydantic import BaseModel
+from typing import Dict, Any
+
+
+class HealthResponse(BaseModel):
+    """Response schema for the health check endpoint"""
+    status: str
+    version: str
+    details: Dict[str, Any]

api/schemas/todo.py

@@ -0,0 +1,34 @@
+from pydantic import BaseModel, Field
+from typing import Optional
+from datetime import datetime
+
+
+class TodoBase(BaseModel):
+    """Base Todo schema with common attributes"""
+    title: str = Field(..., min_length=1, max_length=100, description="Title of the todo")
+    description: Optional[str] = Field(None, max_length=500, description="Detailed description of the todo")
+    completed: bool = Field(False, description="Whether the todo is completed")
+
+
+class TodoCreate(TodoBase):
+    """Schema for creating a new todo"""
+    pass
+
+
+class TodoUpdate(BaseModel):
+    """Schema for updating an existing todo, all fields are optional"""
+    title: Optional[str] = Field(None, min_length=1, max_length=100, description="Title of the todo")
+    description: Optional[str] = Field(None, max_length=500, description="Detailed description of the todo")
+    completed: Optional[bool] = Field(None, description="Whether the todo is completed")
+
+
+class TodoResponse(TodoBase):
+    """Schema for todo response that includes database fields"""
+    id: int
+    created_at: datetime
+    updated_at: Optional[datetime] = None
+
+    class Config:
+        """ORM mode config for the TodoResponse schema"""
+        orm_mode = True
+        from_attributes = True

db/database.py

@@ -0,0 +1,39 @@
+from pathlib import Path
+from sqlalchemy import create_engine
+from sqlalchemy.ext.declarative import declarative_base
+from sqlalchemy.orm import sessionmaker
+
+# Create database directory if it doesn't exist
+DB_DIR = Path("/app") / "storage" / "db"
+DB_DIR.mkdir(parents=True, exist_ok=True)
+
+# Database URL
+SQLALCHEMY_DATABASE_URL = f"sqlite:///{DB_DIR}/db.sqlite"
+
+# Create engine
+engine = create_engine(
+    SQLALCHEMY_DATABASE_URL,
+    connect_args={"check_same_thread": False}
+)
+
+# Create session factory
+SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
+
+# Create base class for models
+Base = declarative_base()
+
+def get_db():
+    """
+    Get database session dependency
+    """
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()
+
+def create_tables():
+    """
+    Create all tables defined in models
+    """
+    Base.metadata.create_all(bind=engine)

db/models.py

@@ -0,0 +1,17 @@
+from sqlalchemy import Column, Integer, String, Boolean, DateTime
+from sqlalchemy.sql import func
+from .database import Base
+
+
+class Todo(Base):
+    """
+    Todo model representing a task to be done
+    """
+    __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), onupdate=func.now())

main.py

@@ -0,0 +1,32 @@
+from fastapi import FastAPI
+from fastapi.middleware.cors import CORSMiddleware
+import uvicorn
+from api.routers import todo_router, health_router
+from db.database import create_tables
+
+app = FastAPI(
+    title="SimpleTodoApp API",
+    description="API for a simple todo application",
+    version="0.1.0",
+)
+
+# CORS settings
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=["*"],  # For development, in production specify your frontend domain
+    allow_credentials=True,
+    allow_methods=["*"],
+    allow_headers=["*"],
+)
+
+# Include routers
+app.include_router(todo_router.router, prefix="/api/todos", tags=["todos"])
+app.include_router(health_router.router, tags=["health"])
+
+# Create database tables on startup
+@app.on_event("startup")
+async def startup():
+    create_tables()
+
+if __name__ == "__main__":
+    uvicorn.run("main:app", host="0.0.0.0", port=8000, reload=True)

migrations/README

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

migrations/env.py

@@ -0,0 +1,79 @@
+from logging.config import fileConfig
+
+from sqlalchemy import engine_from_config
+from sqlalchemy import pool
+
+from alembic import context
+
+from db.models 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
+# from myapp import mymodel
+# target_metadata = mymodel.Base.metadata
+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:
+        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()

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/1_initial_create_todos_table.py

@@ -0,0 +1,35 @@
+"""Initial create todos table
+
+Revision ID: 1_initial_create_todos_table
+Revises: 
+Create Date: 2023-09-20 12:00:00.000000
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = '1_initial_create_todos_table'
+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(), default=False),
+        sa.Column('created_at', sa.DateTime(timezone=True), server_default=sa.func.now()),
+        sa.Column('updated_at', sa.DateTime(timezone=True), onupdate=sa.func.now()),
+        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')

pyproject.toml

@@ -0,0 +1,8 @@
+[tool.ruff]
+line-length = 100
+target-version = "py39"
+select = ["E", "F", "I", "W", "N", "B", "A", "COM", "C4", "UP", "S", "BLE", "T10", "ISC", "G"]
+ignore = []
+
+[tool.ruff.isort]
+known-third-party = ["fastapi", "sqlalchemy", "pydantic", "alembic"]

requirements.txt

@@ -0,0 +1,9 @@
+fastapi>=0.101.0
+uvicorn>=0.23.2
+sqlalchemy>=2.0.19
+pydantic>=2.1.1
+alembic>=1.11.1
+ruff>=0.0.280
+python-dotenv>=1.0.0
+python-multipart>=0.0.6
+pathlib>=1.0.1