Create a simple Todo app with FastAPI and SQLite

- Set up project structure and FastAPI application
- Create Todo database model with SQLAlchemy
- Configure Alembic for database migrations
- Implement CRUD endpoints for managing Todo items
- Add health check endpoint
- Include comprehensive documentation in README.md
- Configure and apply Ruff linting

README.md

@@ -1,3 +1,107 @@
-# FastAPI Application
+# Simple Todo App with FastAPI and SQLite
 
-This is a FastAPI application bootstrapped by BackendIM, the AI-powered backend generation platform.
+A simple Todo API application built with FastAPI and SQLite that provides CRUD operations for todo items.
+
+## Features
+
+- Create, read, update, and delete todo items
+- RESTful API with FastAPI
+- SQLite database with SQLAlchemy ORM
+- Database migrations with Alembic
+- Automatic API documentation with Swagger UI and ReDoc
+- Health check endpoint
+
+## Project Structure
+
+```
+simpletodoapp/
+├── alembic.ini                 # Alembic configuration
+├── migrations/                 # Database migration scripts
+├── app/                        # Application package
+│   ├── api/                    # API routes
+│   │   └── routes/             # Route modules 
+│   │       ├── health.py       # Health check endpoint
+│   │       └── todos.py        # Todo endpoints
+│   ├── core/                   # Core modules
+│   │   └── config.py           # App configuration
+│   ├── crud/                   # CRUD operations
+│   │   └── todo.py             # Todo CRUD operations
+│   ├── db/                     # Database setup
+│   │   └── session.py          # DB session and engine
+│   ├── models/                 # SQLAlchemy models
+│   │   └── todo.py             # Todo model
+│   └── schemas/                # Pydantic schemas
+│       └── todo.py             # Todo schemas
+├── main.py                     # FastAPI application creation
+└── requirements.txt            # Python dependencies
+```
+
+## Getting Started
+
+### Prerequisites
+
+- Python 3.8 or higher
+- pip (Python package installer)
+
+### Installation
+
+1. Clone the repository:
+```bash
+git clone https://github.com/yourusername/simpletodoapp.git
+cd simpletodoapp
+```
+
+2. Install the dependencies:
+```bash
+pip install -r requirements.txt
+```
+
+3. Run the application:
+```bash
+uvicorn main:app --reload
+```
+
+The application will be available at http://localhost:8000.
+
+### API Documentation
+
+After starting the application, you can access the API documentation at:
+- Swagger UI: http://localhost:8000/docs
+- ReDoc: http://localhost:8000/redoc
+
+## API Endpoints
+
+### Health Check
+- `GET /health` - Check the health of the application and database connection
+
+### Todo Operations
+- `GET /api/v1/todos` - Retrieve all todos (with pagination)
+- `POST /api/v1/todos` - Create a new todo
+- `GET /api/v1/todos/{todo_id}` - Retrieve a specific todo
+- `PUT /api/v1/todos/{todo_id}` - Update a specific todo
+- `DELETE /api/v1/todos/{todo_id}` - Delete a specific todo
+
+## Database Migrations
+
+Migrations are managed by Alembic:
+
+```bash
+# Apply all migrations
+alembic upgrade head
+
+# Generate a new migration (after modifying models)
+alembic revision --autogenerate -m "description"
+```
+
+## Development
+
+### Running Tests
+```bash
+pytest
+```
+
+### Linting
+```bash
+ruff check .
+ruff format .
+```

alembic.ini

@@ -0,0 +1,110 @@
+# A generic, single database configuration.
+
+[alembic]
+# path to migration scripts
+script_location = migrations
+
+# template used to generate migration file names; The default value is %%(rev)s_%%(slug)s
+# Uncomment the line below if you want the files to be prepended with date and time
+# see https://alembic.sqlalchemy.org/en/latest/tutorial.html#editing-the-ini-file
+# for all available tokens
+# file_template = %%(year)d_%%(month).2d_%%(day).2d_%%(hour).2d%%(minute).2d-%%(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
+
+# version location specification; This defaults
+# to migrations/versions.  When using multiple version
+# directories, initial revisions must be specified with --version-path.
+# The path separator used here should be the separator specified by "version_path_separator" below.
+# version_locations = %(here)s/bar:%(here)s/bat:migrations/versions
+
+# version path separator; As mentioned above, this is the character used to split
+# version_locations. The default within new alembic.ini files is "os", which uses os.pathsep.
+# If this key is omitted entirely, it falls back to the legacy behavior of splitting on spaces and/or commas.
+# Valid values for version_path_separator are:
+#
+# version_path_separator = :
+# version_path_separator = ;
+# version_path_separator = space
+version_path_separator = os  # Use os.pathsep. Default configuration used for new projects.
+
+# set to 'true' to search source files recursively
+# in each "version_locations" directory
+# new in Alembic version 1.10
+# recursive_version_locations = false
+
+# the output encoding used when revision files
+# are written from script.py.mako
+# output_encoding = utf-8
+
+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

app/api/routes/health.py

@@ -0,0 +1,19 @@
+from fastapi import APIRouter, Depends
+from sqlalchemy.orm import Session
+
+from app.db.session import get_db
+
+router = APIRouter()
+
+
+@router.get("/health", tags=["health"])
+def health_check(db: Session = Depends(get_db)):
+    """
+    Health check endpoint that verifies database connection
+    """
+    try:
+        # Execute a simple query to verify the database is working
+        db.execute("SELECT 1")
+        return {"status": "healthy", "database": "connected"}
+    except Exception as e:
+        return {"status": "unhealthy", "database": str(e)}

app/api/routes/todos.py

@@ -0,0 +1,69 @@
+from typing import List
+
+from fastapi import APIRouter, Depends, HTTPException, Query, status
+from sqlalchemy.orm import Session
+
+from app import crud
+from app.db.session import get_db
+from app.schemas.todo import Todo, TodoCreate, TodoUpdate
+
+router = APIRouter(prefix="/todos", tags=["todos"])
+
+
+@router.get("/", response_model=List[Todo])
+def get_todos(
+    skip: int = Query(0, description="Skip the first N items"),
+    limit: int = Query(100, description="Limit the number of items returned"),
+    db: Session = Depends(get_db),
+):
+    """
+    Get all todos with pagination
+    """
+    return crud.todo.get_todos(db=db, skip=skip, limit=limit)
+
+
+@router.post("/", response_model=Todo, status_code=status.HTTP_201_CREATED)
+def create_todo(todo: TodoCreate, db: Session = Depends(get_db)):
+    """
+    Create a new todo
+    """
+    return crud.todo.create_todo(db=db, todo=todo)
+
+
+@router.get("/{todo_id}", response_model=Todo)
+def get_todo(todo_id: int, db: Session = Depends(get_db)):
+    """
+    Get a specific todo by ID
+    """
+    db_todo = crud.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.put("/{todo_id}", response_model=Todo)
+def update_todo(todo_id: int, todo: TodoUpdate, db: Session = Depends(get_db)):
+    """
+    Update a todo
+    """
+    db_todo = crud.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("/{todo_id}", status_code=status.HTTP_204_NO_CONTENT, response_model=None)
+def delete_todo(todo_id: int, db: Session = Depends(get_db)):
+    """
+    Delete a todo
+    """
+    success = crud.todo.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/core/config.py

@@ -0,0 +1,23 @@
+from typing import List, Union
+
+from pydantic import AnyHttpUrl, validator
+from pydantic_settings import BaseSettings
+
+
+class Settings(BaseSettings):
+    API_V1_STR: str = "/api/v1"
+    PROJECT_NAME: str = "SimpleTodoApp"
+
+    # CORS
+    BACKEND_CORS_ORIGINS: List[AnyHttpUrl] = []
+
+    @validator("BACKEND_CORS_ORIGINS", pre=True)
+    def assemble_cors_origins(cls, v: Union[str, List[str]]) -> Union[List[str], str]:
+        if isinstance(v, str) and not v.startswith("["):
+            return [i.strip() for i in v.split(",")]
+        elif isinstance(v, (list, str)):
+            return v
+        raise ValueError(v)
+
+
+settings = Settings()

app/crud/todo.py

@@ -0,0 +1,62 @@
+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_todos(db: Session, skip: int = 0, limit: int = 100) -> List[Todo]:
+    """
+    Get all todo items 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 item by ID
+    """
+    return db.query(Todo).filter(Todo.id == todo_id).first()
+
+
+def create_todo(db: Session, todo: TodoCreate) -> Todo:
+    """
+    Create a new todo item
+    """
+    db_todo = Todo(title=todo.title, description=todo.description, completed=todo.completed)
+    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 a todo item
+    """
+    db_todo = get_todo(db, todo_id)
+    if not db_todo:
+        return None
+
+    update_data = todo.model_dump(exclude_unset=True)
+
+    for field, value in update_data.items():
+        setattr(db_todo, field, value)
+
+    db.commit()
+    db.refresh(db_todo)
+    return db_todo
+
+
+def delete_todo(db: Session, todo_id: int) -> bool:
+    """
+    Delete a todo item
+    """
+    db_todo = get_todo(db, todo_id)
+    if not db_todo:
+        return False
+
+    db.delete(db_todo)
+    db.commit()
+    return True

app/db/session.py

@@ -0,0 +1,25 @@
+from pathlib import Path
+
+from sqlalchemy import create_engine
+from sqlalchemy.ext.declarative import declarative_base
+from sqlalchemy.orm import sessionmaker
+
+# Create database directory
+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)
+
+Base = declarative_base()
+
+
+# Dependency
+def get_db():
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()

app/models/todo.py

@@ -0,0 +1,17 @@
+from sqlalchemy import Boolean, Column, DateTime, Integer, String
+from sqlalchemy.sql import func
+
+from app.db.session import Base
+
+
+class Todo(Base):
+    """Database model for Todo items"""
+
+    __tablename__ = "todos"
+
+    id = Column(Integer, primary_key=True, index=True)
+    title = Column(String, index=True)
+    description = Column(String, nullable=True)
+    completed = Column(Boolean, default=False)
+    created_at = Column(DateTime(timezone=True), default=func.now())
+    updated_at = Column(DateTime(timezone=True), default=func.now(), onupdate=func.now())

app/schemas/todo.py

@@ -0,0 +1,43 @@
+from datetime import datetime
+from typing import Optional
+
+from pydantic import BaseModel
+
+
+class TodoBase(BaseModel):
+    """Base schema for Todo items"""
+
+    title: str
+    description: Optional[str] = None
+    completed: bool = False
+
+
+class TodoCreate(TodoBase):
+    """Schema for creating a new Todo item"""
+
+    pass
+
+
+class TodoUpdate(BaseModel):
+    """Schema for updating a Todo item"""
+
+    title: Optional[str] = None
+    description: Optional[str] = None
+    completed: Optional[bool] = None
+
+
+class TodoInDBBase(TodoBase):
+    """Base schema for Todo items from the database"""
+
+    id: int
+    created_at: datetime
+    updated_at: datetime
+
+    class Config:
+        from_attributes = True
+
+
+class Todo(TodoInDBBase):
+    """Schema for Todo items returned from the API"""
+
+    pass

main.py

@@ -0,0 +1,31 @@
+from fastapi import FastAPI
+from fastapi.middleware.cors import CORSMiddleware
+
+from app.api.routes import health, todos
+from app.core.config import settings
+
+app = FastAPI(
+    title=settings.PROJECT_NAME,
+    openapi_url=f"{settings.API_V1_STR}/openapi.json",
+    description="A simple Todo API using FastAPI and SQLite",
+    version="0.1.0",
+)
+
+# Set all CORS enabled origins
+if settings.BACKEND_CORS_ORIGINS:
+    app.add_middleware(
+        CORSMiddleware,
+        allow_origins=[str(origin) for origin in settings.BACKEND_CORS_ORIGINS],
+        allow_credentials=True,
+        allow_methods=["*"],
+        allow_headers=["*"],
+    )
+
+# Include routers
+app.include_router(todos.router, prefix=settings.API_V1_STR)
+app.include_router(health.router)
+
+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.

migrations/env.py

@@ -0,0 +1,81 @@
+from logging.config import fileConfig
+
+from alembic import context
+from sqlalchemy import engine_from_config, pool
+
+# Add model metadata for 'autogenerate' support
+from app.db.session import Base
+from app.models.todo import Todo  # noqa
+
+# 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.
+if config.config_file_name is not None:
+    fileConfig(config.config_file_name)
+
+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() -> None:
+    """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"},
+        render_as_batch=True,
+    )
+
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+def run_migrations_online() -> None:
+    """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,
+            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() -> None:
+    ${upgrades if upgrades else "pass"}
+
+
+def downgrade() -> None:
+    ${downgrades if downgrades else "pass"}

migrations/versions/0001_create_todos_table.py

@@ -0,0 +1,45 @@
+"""create todos table
+
+Revision ID: 0001
+Revises:
+Create Date: 2023-11-10
+
+"""
+
+import sqlalchemy as sa
+from alembic import op
+
+# revision identifiers, used by Alembic.
+revision = "0001"
+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=False, default=False),
+        sa.Column(
+            "created_at", sa.DateTime(timezone=True), nullable=False, server_default=sa.func.now()
+        ),
+        sa.Column(
+            "updated_at",
+            sa.DateTime(timezone=True),
+            nullable=False,
+            server_default=sa.func.now(),
+            onupdate=sa.func.now(),
+        ),
+        sa.PrimaryKeyConstraint("id"),
+    )
+    op.create_index(op.f("ix_todos_id"), "todos", ["id"], unique=False)
+    op.create_index(op.f("ix_todos_title"), "todos", ["title"], unique=False)
+
+
+def downgrade() -> None:
+    op.drop_index(op.f("ix_todos_title"), table_name="todos")
+    op.drop_index(op.f("ix_todos_id"), table_name="todos")
+    op.drop_table("todos")

pyproject.toml

@@ -0,0 +1,20 @@
+[tool.ruff]
+target-version = "py38"
+line-length = 100
+
+[tool.ruff.lint]
+select = [
+    "E",  # pycodestyle errors
+    "F",  # pyflakes
+    "B",  # flake8-bugbear
+    "I",  # isort
+]
+ignore = ["B008"]  # Allow Depends() in function defaults which is FastAPI's pattern
+
+[tool.ruff.format]
+quote-style = "double"
+indent-style = "space"
+line-ending = "auto"
+
+[tool.ruff.lint.isort]
+known-third-party = ["fastapi", "pydantic", "sqlalchemy", "alembic"]

requirements.txt

@@ -0,0 +1,10 @@
+fastapi>=0.104.0
+uvicorn>=0.23.2
+sqlalchemy>=2.0.23
+alembic>=1.12.1
+pydantic>=2.4.2
+pydantic-settings>=2.0.3
+python-multipart>=0.0.6
+ruff>=0.1.3
+pytest>=7.4.3
+httpx>=0.25.1