Create simple Todo application with FastAPI and SQLite

- Set up project structure with FastAPI and SQLite
- Created Todo model and database schemas
- Implemented CRUD operations for Todo items
- Added Alembic for database migrations
- Added health check endpoint
- Used Ruff for code linting and formatting
- Updated README with project documentation

README.md

@@ -1,3 +1,98 @@
-# 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
+- Filter Todos by completion status
+- Health check endpoint
+- SQLite database with SQLAlchemy ORM
+- Alembic for database migrations
+
+## Project Structure
+
+```
+simpletodoapp/
+├── app/
+│   ├── api/
+│   │   ├── endpoints/
+│   │   │   ├── health.py
+│   │   │   └── todos.py
+│   ├── core/
+│   │   └── config.py
+│   ├── db/
+│   │   ├── crud.py
+│   │   └── session.py
+│   ├── models/
+│   │   └── todo.py
+│   └── schemas/
+│       └── todo.py
+├── migrations/
+│   ├── versions/
+│   │   └── e4fe0b756bcd_create_todos_table.py
+│   ├── env.py
+│   ├── README
+│   └── script.py.mako
+├── storage/
+│   └── db/
+├── alembic.ini
+├── main.py
+└── requirements.txt
+```
+
+## Installation
+
+1. Clone the repository
+2. Install dependencies:
+
+```bash
+pip install -r requirements.txt
+```
+
+## Running the Application
+
+```bash
+uvicorn main:app --reload
+```
+
+The API will be available at `http://localhost:8000`.
+
+API Documentation will be available at:
+- Swagger UI: `http://localhost:8000/docs`
+- ReDoc: `http://localhost:8000/redoc`
+
+## Database Migration
+
+The application uses Alembic for database migrations. 
+
+To apply migrations:
+
+```bash
+alembic upgrade head
+```
+
+## API Endpoints
+
+### Health Check
+- `GET /health` - Check the health of the application
+
+### Todo Endpoints
+- `GET /api/todos` - List all todos (with optional filtering)
+- `POST /api/todos` - Create a new todo
+- `GET /api/todos/{todo_id}` - Get a specific todo
+- `PUT /api/todos/{todo_id}` - Update a todo
+- `DELETE /api/todos/{todo_id}` - Delete a todo
+
+## Example Todo Object
+
+```json
+{
+  "id": 1,
+  "title": "Buy groceries",
+  "description": "Milk, bread, eggs",
+  "completed": false,
+  "created_at": "2023-08-01T10:00:00",
+  "updated_at": "2023-08-01T10:00:00"
+}
+```

alembic.ini

@@ -0,0 +1,100 @@
+# 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
+
+# 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"
+# 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. Valid values are:
+#
+# version_path_separator = :
+# version_path_separator = ;
+# version_path_separator = space
+version_path_separator = os  # default: use os.pathsep
+
+# 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/endpoints/health.py

@@ -0,0 +1,27 @@
+from fastapi import APIRouter, Depends
+from pydantic import BaseModel
+from sqlalchemy.orm import Session
+
+from app.db.session import get_db
+
+router = APIRouter()
+
+
+class HealthResponse(BaseModel):
+    status: str
+    db_status: str
+
+
+@router.get("/health", response_model=HealthResponse)
+def health_check(db: Session = Depends(get_db)):
+    """
+    Check the health of the application.
+    """
+    # Check DB connection
+    try:
+        db.execute("SELECT 1")
+        db_status = "healthy"
+    except Exception:
+        db_status = "unhealthy"
+
+    return HealthResponse(status="healthy", db_status=db_status)

app/api/endpoints/todos.py

@@ -0,0 +1,68 @@
+from typing import Optional
+
+from fastapi import APIRouter, Depends, HTTPException, status
+from sqlalchemy.orm import Session
+
+from app.db import crud
+from app.db.session import get_db
+from app.schemas.todo import Todo, TodoCreate, TodoUpdate
+
+router = APIRouter()
+
+
+@router.get("/", response_model=list[Todo])
+def read_todos(
+    skip: int = 0,
+    limit: int = 100,
+    completed: Optional[bool] = None,
+    db: Session = Depends(get_db),
+):
+    """
+    Retrieve todos.
+    - Optional filter by completed status
+    - Optional pagination with skip and limit parameters
+    """
+    todos = crud.get_todos(db, skip=skip, limit=limit, completed=completed)
+    return todos
+
+
+@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 item.
+    """
+    return crud.create_todo(db=db, todo_create=todo)
+
+
+@router.get("/{todo_id}", response_model=Todo)
+def read_todo(todo_id: int, db: Session = Depends(get_db)):
+    """
+    Get a specific todo by ID.
+    """
+    db_todo = crud.get_todo(db, todo_id=todo_id)
+    if db_todo is None:
+        raise HTTPException(status_code=404, detail="Todo 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.update_todo(db, todo_id=todo_id, todo_update=todo)
+    if db_todo is None:
+        raise HTTPException(status_code=404, detail="Todo 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.
+    """
+    deleted = crud.delete_todo(db, todo_id=todo_id)
+    if not deleted:
+        raise HTTPException(status_code=404, detail="Todo not found")

app/core/config.py

@@ -0,0 +1,24 @@
+from pathlib import Path
+
+from pydantic_settings import BaseSettings
+
+
+class Settings(BaseSettings):
+    PROJECT_NAME: str = "SimpleTodoApp"
+    PROJECT_DESCRIPTION: str = (
+        "A simple Todo application API built with FastAPI and SQLite"
+    )
+    PROJECT_VERSION: str = "0.1.0"
+
+    # Database configuration
+    DB_DIR: Path = Path("/app") / "storage" / "db"
+    SQLALCHEMY_DATABASE_URL: str = f"sqlite:///{DB_DIR}/db.sqlite"
+
+    class Config:
+        env_file = ".env"
+
+
+settings = Settings()
+
+# Create DB directory if it doesn't exist
+settings.DB_DIR.mkdir(parents=True, exist_ok=True)

app/db/crud.py

@@ -0,0 +1,55 @@
+from typing import 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]:
+    return db.query(Todo).filter(Todo.id == todo_id).first()
+
+
+def get_todos(
+    db: Session, skip: int = 0, limit: int = 100, completed: Optional[bool] = None
+) -> list[Todo]:
+    query = db.query(Todo)
+    if completed is not None:
+        query = query.filter(Todo.completed == completed)
+    return query.offset(skip).limit(limit).all()
+
+
+def create_todo(db: Session, todo_create: TodoCreate) -> Todo:
+    db_todo = Todo(
+        title=todo_create.title,
+        description=todo_create.description,
+        completed=todo_create.completed,
+    )
+    db.add(db_todo)
+    db.commit()
+    db.refresh(db_todo)
+    return db_todo
+
+
+def update_todo(db: Session, todo_id: int, todo_update: TodoUpdate) -> Optional[Todo]:
+    db_todo = get_todo(db, todo_id)
+    if db_todo is None:
+        return None
+
+    update_data = todo_update.model_dump(exclude_unset=True)
+    for key, value in update_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:
+    db_todo = get_todo(db, todo_id)
+    if db_todo is None:
+        return False
+
+    db.delete(db_todo)
+    db.commit()
+    return True

app/db/session.py

@@ -0,0 +1,23 @@
+from sqlalchemy import create_engine
+from sqlalchemy.ext.declarative import declarative_base
+from sqlalchemy.orm import sessionmaker
+
+from app.core.config import settings
+
+engine = create_engine(
+    settings.SQLALCHEMY_DATABASE_URL,
+    connect_args={"check_same_thread": False},  # SQLite specific
+)
+
+SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
+
+Base = declarative_base()
+
+
+# Dependency to get DB session
+def get_db():
+    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 datetime import datetime
+
+from sqlalchemy import Boolean, Column, DateTime, Integer, String
+
+from app.db.session import Base
+
+
+class Todo(Base):
+    __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, default=datetime.utcnow)
+    updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)

app/schemas/__init__.py

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

app/schemas/todo.py

@@ -0,0 +1,33 @@
+from datetime import datetime
+from typing import Optional
+
+from pydantic import BaseModel
+
+
+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 TodoInDB(TodoBase):
+    id: int
+    created_at: datetime
+    updated_at: datetime
+
+    class Config:
+        from_attributes = True
+
+
+class Todo(TodoInDB):
+    pass

main.py

@@ -0,0 +1,29 @@
+from fastapi import FastAPI
+from fastapi.middleware.cors import CORSMiddleware
+
+from app.api.endpoints import health, todos
+from app.core.config import settings
+
+app = FastAPI(
+    title=settings.PROJECT_NAME,
+    description=settings.PROJECT_DESCRIPTION,
+    version=settings.PROJECT_VERSION,
+)
+
+# Add CORS middleware
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=["*"],
+    allow_credentials=True,
+    allow_methods=["*"],
+    allow_headers=["*"],
+)
+
+# Include routers
+app.include_router(health.router, tags=["health"])
+app.include_router(todos.router, prefix="/api/todos", tags=["todos"])
+
+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 SQLite.

migrations/env.py

@@ -0,0 +1,81 @@
+from logging.config import fileConfig
+
+from alembic import context
+from sqlalchemy import engine_from_config, pool
+
+from app.db.session 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:
+        # For SQLite, use render_as_batch=True
+        is_sqlite = connection.dialect.name == "sqlite"
+        context.configure(
+            connection=connection,
+            target_metadata=target_metadata,
+            # Important for SQLite to allow column alterations
+            render_as_batch=is_sqlite,
+        )
+
+        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/e4fe0b756bcd_create_todos_table.py

@@ -0,0 +1,42 @@
+"""create todos table
+
+Revision ID: e4fe0b756bcd
+Revises:
+Create Date: 2023-08-01 10:00:00.000000
+
+"""
+
+import sqlalchemy as sa
+from alembic import op
+
+# revision identifiers, used by Alembic.
+revision = "e4fe0b756bcd"
+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(), default=sa.func.current_timestamp()),
+        sa.Column(
+            "updated_at",
+            sa.DateTime(),
+            default=sa.func.current_timestamp(),
+            onupdate=sa.func.current_timestamp(),
+        ),
+        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():
+    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 +1,21 @@
+[tool.ruff]
+line-length = 88
+target-version = "py39"
+
+[tool.ruff.lint]
+select = ["E", "F", "I", "N", "W", "B", "UP", "ASYNC", "C4", "PYI", "PL", "RUF", "SIM"]
+ignore = ["B008"]  # Allow function calls in argument defaults (FastAPI uses this pattern a lot)
+
+[tool.ruff.lint.per-file-ignores]
+"__init__.py" = ["F401", "E402"]
+"migrations/*" = ["E402"]
+
+[tool.ruff.lint.isort]
+known-first-party = ["app"]
+
+[tool.ruff.format]
+quote-style = "double"
+indent-style = "space"
+line-ending = "auto"
+skip-magic-trailing-comma = false
+docstring-code-format = true

requirements.txt

@@ -0,0 +1,7 @@
+fastapi>=0.68.0
+uvicorn>=0.15.0
+sqlalchemy>=1.4.0
+alembic>=1.7.0
+pydantic>=2.0.0
+python-dotenv>=0.19.0
+ruff>=0.0.270