Create Todo API application with FastAPI and SQLite

README.md

@@ -1,3 +1,102 @@
-# FastAPI Application
+# Todo API
 
-This is a FastAPI application bootstrapped by BackendIM, the AI-powered backend generation platform.
+A simple REST API for managing todo items built with FastAPI and SQLite.
+
+## Features
+
+- Create, read, update, and delete todo items
+- Filter todos by completion status
+- Input validation with Pydantic
+- Database migrations with Alembic
+- Error handling and structured responses
+- Health check endpoint
+- API documentation with Swagger UI
+
+## Technologies Used
+
+- [FastAPI](https://fastapi.tiangolo.com/) - Modern web framework for building APIs
+- [SQLAlchemy](https://www.sqlalchemy.org/) - SQL toolkit and ORM
+- [Pydantic](https://docs.pydantic.dev/) - Data validation and settings management
+- [Alembic](https://alembic.sqlalchemy.org/) - Database migration tool
+- [SQLite](https://www.sqlite.org/) - File-based SQL database
+- [Uvicorn](https://www.uvicorn.org/) - ASGI server
+- [Ruff](https://beta.ruff.rs/docs/) - Python linter and formatter
+
+## Project Structure
+
+```
+todoapi/
+├── alembic.ini              # Alembic configuration
+├── app/                     # Application package
+│   ├── api/                 # API endpoints
+│   │   ├── endpoints/       # Endpoint handlers
+│   │   │   └── todos.py     # Todo endpoints
+│   │   ├── api.py           # API router
+│   │   └── errors.py        # Error handling
+│   ├── db/                  # Database
+│   │   └── database.py      # Database configuration
+│   ├── models/              # SQLAlchemy models
+│   │   └── todo.py          # Todo model
+│   └── schemas/             # Pydantic schemas
+│       └── todo.py          # Todo schemas
+├── main.py                  # Application entry point
+├── migrations/              # Database migrations
+│   ├── env.py               # Alembic environment
+│   ├── script.py.mako       # Migration template
+│   └── versions/            # Migration scripts
+├── pyproject.toml           # Project configuration
+└── requirements.txt         # Dependencies
+```
+
+## API Endpoints
+
+- `GET /health` - Health check endpoint
+- `GET /todos` - List all todo items (with optional filtering)
+- `GET /todos/{todo_id}` - Get a specific todo item
+- `POST /todos` - Create a new todo item
+- `PUT /todos/{todo_id}` - Update a todo item
+- `DELETE /todos/{todo_id}` - Delete a todo item
+
+## Getting Started
+
+### Prerequisites
+
+- Python 3.9 or higher
+
+### Installation
+
+1. Clone the repository
+2. Install dependencies:
+
+```bash
+pip install -r requirements.txt
+```
+
+3. Run the application:
+
+```bash
+uvicorn main:app --reload
+```
+
+4. Visit the API documentation at http://localhost:8000/docs
+
+## Database Migrations
+
+The application uses Alembic for database migrations:
+
+```bash
+# Apply migrations
+alembic upgrade head
+
+# Create a new migration (after modifying models)
+alembic revision --autogenerate -m "description"
+```
+
+## Development
+
+To lint and format the code:
+
+```bash
+ruff check .
+ruff check --fix .
+```

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 URL example
+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/api/api.py

@@ -0,0 +1,7 @@
+from fastapi import APIRouter
+
+from app.api.endpoints import todos
+
+api_router = APIRouter()
+
+api_router.include_router(todos.router, prefix="/todos", tags=["todos"])

app/api/endpoints/todos.py

@@ -0,0 +1,95 @@
+from typing import Optional
+
+from fastapi import APIRouter, Depends, HTTPException, status
+from sqlalchemy.orm import Session
+
+from app.db.database import get_db
+from app.models.todo import Todo
+from app.schemas.todo import Todo as TodoSchema
+from app.schemas.todo import TodoCreate, TodoUpdate
+
+router = APIRouter()
+
+
+@router.post("/", response_model=TodoSchema, status_code=status.HTTP_201_CREATED)
+def create_todo(todo: TodoCreate, db: Session = Depends(get_db)):
+    """
+    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
+
+
+@router.get("/", response_model=list[TodoSchema])
+def read_todos(
+    skip: int = 0, 
+    limit: int = 100, 
+    completed: Optional[bool] = None,
+    db: Session = Depends(get_db)
+):
+    """
+    Retrieve all todo items with optional filtering.
+    """
+    query = db.query(Todo)
+    
+    # Filter by completion status if specified
+    if completed is not None:
+        query = query.filter(Todo.completed == completed)
+    
+    todos = query.offset(skip).limit(limit).all()
+    return todos
+
+
+@router.get("/{todo_id}", response_model=TodoSchema)
+def read_todo(todo_id: int, db: Session = Depends(get_db)):
+    """
+    Retrieve a specific todo item by ID.
+    """
+    db_todo = db.query(Todo).filter(Todo.id == todo_id).first()
+    if db_todo is None:
+        raise HTTPException(status_code=404, detail="Todo not found")
+    return db_todo
+
+
+@router.put("/{todo_id}", response_model=TodoSchema)
+def update_todo(todo_id: int, todo: TodoUpdate, db: Session = Depends(get_db)):
+    """
+    Update a todo item.
+    """
+    db_todo = db.query(Todo).filter(Todo.id == todo_id).first()
+    if db_todo is None:
+        raise HTTPException(status_code=404, detail="Todo not found")
+    
+    # Update fields that are provided
+    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
+
+
+@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 item.
+    """
+    db_todo = db.query(Todo).filter(Todo.id == todo_id).first()
+    if db_todo is None:
+        raise HTTPException(status_code=404, detail="Todo not found")
+    
+    db.delete(db_todo)
+    db.commit()
+    return None

app/api/errors.py

@@ -0,0 +1,58 @@
+from fastapi import HTTPException, Request, status
+from fastapi.responses import JSONResponse
+from pydantic import ValidationError
+
+
+class APIError(HTTPException):
+    def __init__(
+        self,
+        status_code: int,
+        detail: str,
+        error_code: str = None,
+    ):
+        super().__init__(status_code=status_code, detail=detail)
+        self.error_code = error_code
+
+
+async def http_error_handler(request: Request, exc: HTTPException) -> JSONResponse:
+    """
+    Handle HTTP exceptions.
+    """
+    return JSONResponse(
+        status_code=exc.status_code,
+        content={"detail": exc.detail}
+    )
+
+
+async def api_error_handler(request: Request, exc: APIError) -> JSONResponse:
+    """
+    Handle custom API exceptions.
+    """
+    headers = getattr(exc, "headers", None)
+    
+    if exc.error_code:
+        content = {"detail": exc.detail, "code": exc.error_code}
+    else:
+        content = {"detail": exc.detail}
+    
+    return JSONResponse(
+        status_code=exc.status_code,
+        content=content,
+        headers=headers,
+    )
+
+
+async def validation_error_handler(
+    request: Request, 
+    exc: ValidationError
+) -> JSONResponse:
+    """
+    Handle validation errors.
+    """
+    return JSONResponse(
+        status_code=status.HTTP_422_UNPROCESSABLE_ENTITY,
+        content={
+            "detail": exc.errors(),
+            "body": exc.body,
+        },
+    )

app/db/database.py

@@ -0,0 +1,29 @@
+from pathlib import Path
+
+from sqlalchemy import create_engine
+from sqlalchemy.ext.declarative import declarative_base
+from sqlalchemy.orm import sessionmaker
+
+# Create DB directory if it doesn't exist
+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 +1,15 @@
+from sqlalchemy import Boolean, Column, DateTime, Integer, String
+from sqlalchemy.sql import func
+
+from app.db.database import Base
+
+
+class Todo(Base):
+    __tablename__ = "todos"
+
+    id = Column(Integer, primary_key=True, index=True)
+    title = Column(String, index=True)
+    description = Column(String)
+    completed = Column(Boolean, default=False)
+    created_at = Column(DateTime(timezone=True), server_default=func.now())
+    updated_at = Column(DateTime(timezone=True), onupdate=func.now())

app/schemas/todo.py

@@ -0,0 +1,33 @@
+from datetime import datetime
+from typing import Optional
+
+from pydantic import BaseModel, Field
+
+
+class TodoBase(BaseModel):
+    title: str = Field(..., min_length=1, max_length=100)
+    description: Optional[str] = Field(None, max_length=1000)
+    completed: bool = False
+
+
+class TodoCreate(TodoBase):
+    pass
+
+
+class TodoUpdate(BaseModel):
+    title: Optional[str] = Field(None, min_length=1, max_length=100)
+    description: Optional[str] = Field(None, max_length=1000)
+    completed: Optional[bool] = None
+
+
+class TodoInDB(TodoBase):
+    id: int
+    created_at: datetime
+    updated_at: Optional[datetime] = None
+
+    class Config:
+        from_attributes = True
+
+
+class Todo(TodoInDB):
+    pass

main.py

@@ -0,0 +1,48 @@
+import uvicorn
+from fastapi import FastAPI, HTTPException, status
+from fastapi.exceptions import RequestValidationError
+from fastapi.middleware.cors import CORSMiddleware
+from pydantic import ValidationError
+
+from app.api.api import api_router
+from app.api.errors import (
+    APIError,
+    api_error_handler,
+    http_error_handler,
+    validation_error_handler,
+)
+
+# Create all tables in the database
+# Comment this out if you're using Alembic migrations
+# Base.metadata.create_all(bind=engine)
+
+app = FastAPI(
+    title="Todo API",
+    description="A simple REST API for managing todo items",
+    version="0.1.0",
+)
+
+# Add exception handlers
+app.add_exception_handler(HTTPException, http_error_handler)
+app.add_exception_handler(APIError, api_error_handler)
+app.add_exception_handler(RequestValidationError, validation_error_handler)
+app.add_exception_handler(ValidationError, validation_error_handler)
+
+# Enable CORS
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=["*"],
+    allow_credentials=True,
+    allow_methods=["*"],
+    allow_headers=["*"],
+)
+
+# Include the API router
+app.include_router(api_router)
+
+@app.get("/health", status_code=status.HTTP_200_OK)
+async def health_check():
+    return {"status": "healthy"}
+
+if __name__ == "__main__":
+    uvicorn.run("main:app", host="0.0.0.0", port=8000, reload=True)

migrations/env.py

@@ -0,0 +1,81 @@
+from logging.config import fileConfig
+
+from sqlalchemy import engine_from_config
+from sqlalchemy import pool
+
+from alembic import context
+
+# 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 app.models.todo import Todo
+from app.db.database import Base
+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/initial_migration.py

@@ -0,0 +1,38 @@
+"""initial migration
+
+Revision ID: 001
+Revises: 
+Create Date: 2023-08-01
+
+"""
+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():
+    # Create todos table
+    op.create_table('todos',
+        sa.Column('id', sa.Integer(), nullable=False),
+        sa.Column('title', sa.String(), nullable=True),
+        sa.Column('description', sa.String(), nullable=True),
+        sa.Column('completed', sa.Boolean(), nullable=True),
+        sa.Column('created_at', sa.DateTime(timezone=True), server_default=sa.text('(CURRENT_TIMESTAMP)'), nullable=True),
+        sa.Column('updated_at', sa.DateTime(timezone=True), nullable=True),
+        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():
+    # Drop todos table
+    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 +1,19 @@
+[tool.ruff]
+line-length = 88
+target-version = "py39"
+exclude = [
+    ".git",
+    ".ruff_cache",
+    ".venv",
+    "venv",
+    "migrations",
+]
+
+[tool.ruff.lint]
+select = ["E", "F", "I", "UP"]
+ignore = []
+fixable = ["ALL"]
+unfixable = []
+
+[tool.ruff.lint.isort]
+known-third-party = ["fastapi", "pydantic", "sqlalchemy", "alembic", "uvicorn"]

requirements.txt

@@ -0,0 +1,10 @@
+fastapi>=0.101.0
+uvicorn>=0.23.2
+pydantic>=2.0.0
+sqlalchemy>=2.0.0
+alembic>=1.11.0
+ruff>=0.0.290
+python-dotenv>=1.0.0
+pydantic-settings>=2.0.0
+httpx>=0.24.1
+pytest>=7.4.0

tests/test_api.py

@@ -0,0 +1,169 @@
+import pytest
+from fastapi.testclient import TestClient
+from sqlalchemy import create_engine
+from sqlalchemy.orm import sessionmaker
+from sqlalchemy.pool import StaticPool
+
+from app.db.database import Base, get_db
+from app.models.todo import Todo
+from main import app
+
+# Setup in-memory SQLite database for testing
+SQLALCHEMY_DATABASE_URL = "sqlite:///:memory:"
+
+engine = create_engine(
+    SQLALCHEMY_DATABASE_URL,
+    connect_args={"check_same_thread": False},
+    poolclass=StaticPool,
+)
+TestingSessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
+
+
+@pytest.fixture
+def test_db():
+    # Create the tables in the test database
+    Base.metadata.create_all(bind=engine)
+    
+    # Create a session for testing
+    db = TestingSessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()
+        
+    # Drop all tables after the test
+    Base.metadata.drop_all(bind=engine)
+
+
+@pytest.fixture
+def client(test_db):
+    # Override the get_db dependency
+    def override_get_db():
+        try:
+            yield test_db
+        finally:
+            pass
+
+    app.dependency_overrides[get_db] = override_get_db
+    
+    with TestClient(app) as c:
+        yield c
+    
+    # Clear overrides
+    app.dependency_overrides.clear()
+
+
+def test_health_check(client):
+    response = client.get("/health")
+    assert response.status_code == 200
+    assert response.json() == {"status": "healthy"}
+
+
+def test_create_todo(client):
+    response = client.post(
+        "/todos/",
+        json={
+            "title": "Test Todo", 
+            "description": "This is a test", 
+            "completed": False
+        },
+    )
+    assert response.status_code == 201
+    data = response.json()
+    assert data["title"] == "Test Todo"
+    assert data["description"] == "This is a test"
+    assert data["completed"] is False
+    assert "id" in data
+    assert "created_at" in data
+
+
+def test_read_todos_empty(client):
+    response = client.get("/todos/")
+    assert response.status_code == 200
+    assert response.json() == []
+
+
+def test_read_todos(client, test_db):
+    # Add a test todo to the database
+    todo = Todo(title="Test Todo", description="Test Description", completed=False)
+    test_db.add(todo)
+    test_db.commit()
+    test_db.refresh(todo)
+    
+    response = client.get("/todos/")
+    assert response.status_code == 200
+    data = response.json()
+    assert len(data) == 1
+    assert data[0]["title"] == "Test Todo"
+    assert data[0]["description"] == "Test Description"
+    assert data[0]["id"] == todo.id
+
+
+def test_read_todo(client, test_db):
+    # Add a test todo to the database
+    todo = Todo(title="Test Todo", description="Test Description", completed=False)
+    test_db.add(todo)
+    test_db.commit()
+    test_db.refresh(todo)
+    
+    response = client.get(f"/todos/{todo.id}")
+    assert response.status_code == 200
+    data = response.json()
+    assert data["title"] == "Test Todo"
+    assert data["description"] == "Test Description"
+    assert data["id"] == todo.id
+
+
+def test_read_todo_not_found(client):
+    response = client.get("/todos/999")
+    assert response.status_code == 404
+    assert response.json() == {"detail": "Todo not found"}
+
+
+def test_update_todo(client, test_db):
+    # Add a test todo to the database
+    todo = Todo(title="Test Todo", description="Test Description", completed=False)
+    test_db.add(todo)
+    test_db.commit()
+    test_db.refresh(todo)
+    
+    response = client.put(
+        f"/todos/{todo.id}",
+        json={"title": "Updated Todo", "completed": True},
+    )
+    assert response.status_code == 200
+    data = response.json()
+    assert data["title"] == "Updated Todo"
+    assert data["description"] == "Test Description"  # Unchanged
+    assert data["completed"] is True  # Updated
+    assert data["id"] == todo.id
+
+
+def test_update_todo_not_found(client):
+    response = client.put(
+        "/todos/999",
+        json={"title": "Updated Todo", "completed": True},
+    )
+    assert response.status_code == 404
+    assert response.json() == {"detail": "Todo not found"}
+
+
+def test_delete_todo(client, test_db):
+    # Add a test todo to the database
+    todo = Todo(title="Test Todo", description="Test Description", completed=False)
+    test_db.add(todo)
+    test_db.commit()
+    test_db.refresh(todo)
+    
+    response = client.delete(f"/todos/{todo.id}")
+    assert response.status_code == 204
+    
+    # Verify it's deleted
+    todo_check = test_db.query(Todo).filter(Todo.id == todo.id).first()
+    assert todo_check is None
+
+
+def test_delete_todo_not_found(client):
+    response = client.delete("/todos/999")
+    assert response.status_code == 404
+    assert response.json() == {"detail": "Todo not found"}