Create Simple Todo API with FastAPI and SQLite

- Set up FastAPI project structure
- Configure SQLAlchemy with SQLite
- Create Todo model and schemas
- Implement CRUD operations
- Add API endpoints for Todo management
- Configure Alembic for database migrations
- Add health check endpoint
- Add comprehensive documentation

README.md

@@ -1,3 +1,119 @@
-# FastAPI Application
+# SimpleTodoAPI
 
-This is a FastAPI application bootstrapped by BackendIM, the AI-powered backend generation platform.
+A simple FastAPI-based RESTful API for managing todo items with SQLite database.
+
+## Features
+
+- Create, read, update, and delete todo items
+- SQLite database with SQLAlchemy ORM
+- Database migrations with Alembic
+- API documentation with Swagger UI and ReDoc
+- Health check endpoint
+- Input validation with Pydantic
+
+## Project Structure
+
+```
+.
+├── alembic.ini                    # Alembic configuration
+├── app                            # Application package
+│   ├── api                        # API endpoints
+│   │   └── routes                 # API routes
+│   │       ├── health.py          # Health check endpoint
+│   │       └── todo.py            # Todo endpoints
+│   ├── core                       # Core module
+│   │   └── config.py              # Application configuration
+│   ├── crud                       # CRUD operations
+│   │   └── todo.py                # Todo CRUD operations
+│   ├── db                         # Database module
+│   │   ├── base.py                # Base DB class and model imports
+│   │   └── session.py             # Database session management
+│   ├── models                     # SQLAlchemy models
+│   │   └── todo.py                # Todo model
+│   └── schemas                    # Pydantic schemas
+│       └── todo.py                # Todo schemas
+├── main.py                        # Application entry point
+├── migrations                     # Alembic migrations
+│   ├── env.py                     # Alembic environment
+│   ├── script.py.mako             # Migration script template
+│   └── versions                   # Migration versions
+│       └── 20231031_010000_create_todos_table.py  # Initial migration
+└── requirements.txt               # Project dependencies
+```
+
+## API Endpoints
+
+- **GET /health** - Health check endpoint
+- **GET /api/v1/todos/** - List all todos
+- **POST /api/v1/todos/** - Create a new todo
+- **GET /api/v1/todos/{todo_id}** - Get a specific todo
+- **PUT /api/v1/todos/{todo_id}** - Update a todo
+- **DELETE /api/v1/todos/{todo_id}** - Delete a todo
+
+## API Documentation
+
+When the server is running, you can access:
+- Swagger UI: http://localhost:8000/docs
+- ReDoc: http://localhost:8000/redoc
+
+## Requirements
+
+- Python 3.7+
+- FastAPI
+- Uvicorn
+- SQLAlchemy
+- Alembic
+- Pydantic
+- Ruff (for linting)
+
+## Installation
+
+```bash
+# Clone the repository
+git clone <repository-url>
+
+# Change to the project directory
+cd simpletodoapi
+
+# Install dependencies
+pip install -r requirements.txt
+```
+
+## Database Setup
+
+```bash
+# Apply database migrations
+alembic upgrade head
+```
+
+## Running the Application
+
+```bash
+# Start the server
+uvicorn main:app --reload
+```
+
+The API will be available at http://localhost:8000.
+
+## Development
+
+### Creating new migrations
+
+```bash
+# Generate a new migration
+alembic revision -m "description of changes"
+```
+
+### Linting
+
+```bash
+# Run ruff linter
+ruff check .
+
+# Run ruff formatter
+ruff format .
+```
+
+## License
+
+This project is licensed under the MIT License.

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 = %%(year)d%%(month).2d%%(day).2d_%%(hour).2d%%(minute).2d%%(second).2d_%%(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/routes/__init__.py

@@ -0,0 +1,4 @@
+from app.api.routes.todo import router as todo_router
+from app.api.routes.health import router as health_router
+
+__all__ = ["todo_router", "health_router"]

app/api/routes/health.py

@@ -0,0 +1,25 @@
+from fastapi import APIRouter, Depends, status
+from sqlalchemy.orm import Session
+
+from app.db.session import get_db
+
+router = APIRouter()
+
+
+@router.get("/health", status_code=status.HTTP_200_OK)
+def health_check(db: Session = Depends(get_db)):
+    """
+    Health check endpoint to verify API is running and database is accessible
+    """
+    try:
+        # Execute a simple query to check if database is accessible
+        db.execute("SELECT 1")
+        return {
+            "status": "healthy",
+            "message": "API is running and database is accessible",
+        }
+    except Exception as e:
+        return {
+            "status": "unhealthy",
+            "message": f"API is running but database is not accessible: {str(e)}",
+        }

app/api/routes/todo.py

@@ -0,0 +1,54 @@
+from typing import List
+
+from fastapi import APIRouter, Depends, HTTPException, status
+from sqlalchemy.orm import Session
+
+from app.crud import todo as todo_crud
+from app.db.session import get_db
+from app.schemas.todo import TodoCreate, TodoResponse, TodoUpdate
+
+router = APIRouter()
+
+
+@router.get("/todos/", response_model=List[TodoResponse])
+def read_todos(skip: int = 0, limit: int = 100, db: Session = Depends(get_db)):
+    """Get all todos with optional pagination"""
+    todos = todo_crud.get_todos(db, skip=skip, limit=limit)
+    return todos
+
+
+@router.post(
+    "/todos/", response_model=TodoResponse, status_code=status.HTTP_201_CREATED
+)
+def create_todo(todo: TodoCreate, db: Session = Depends(get_db)):
+    """Create a new todo"""
+    return todo_crud.create_todo(db=db, todo=todo)
+
+
+@router.get("/todos/{todo_id}", response_model=TodoResponse)
+def read_todo(todo_id: int, db: Session = Depends(get_db)):
+    """Get a specific todo by ID"""
+    db_todo = 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("/todos/{todo_id}", response_model=TodoResponse)
+def update_todo(todo_id: int, todo: TodoUpdate, db: Session = Depends(get_db)):
+    """Update a todo by ID"""
+    db_todo = todo_crud.update_todo(db, todo_id=todo_id, todo=todo)
+    if db_todo is None:
+        raise HTTPException(status_code=404, detail="Todo not found")
+    return db_todo
+
+
+@router.delete(
+    "/todos/{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 by ID"""
+    success = todo_crud.delete_todo(db, todo_id=todo_id)
+    if not success:
+        raise HTTPException(status_code=404, detail="Todo not found")
+    return None

app/core/config.py

@@ -0,0 +1,31 @@
+from pathlib import Path
+from typing import List
+
+from pydantic_settings import BaseSettings, SettingsConfigDict
+
+
+class Settings(BaseSettings):
+    # Project settings
+    PROJECT_NAME: str = "SimpleTodoAPI"
+    PROJECT_DESCRIPTION: str = "A simple FastAPI Todo API with SQLite"
+    PROJECT_VERSION: str = "0.1.0"
+
+    # CORS
+    CORS_ORIGINS: List[str] = ["*"]
+
+    # Database
+    DB_DIR: Path = Path("/app") / "storage" / "db"
+    SQLALCHEMY_DATABASE_URL: str = f"sqlite:///{DB_DIR}/db.sqlite"
+
+    model_config = SettingsConfigDict(
+        case_sensitive=True,
+        env_file=".env",
+        env_file_encoding="utf-8",
+    )
+
+
+# Create instance of Settings
+settings = Settings()
+
+# Ensure database directory exists
+settings.DB_DIR.mkdir(parents=True, exist_ok=True)

app/crud/todo.py

@@ -0,0 +1,53 @@
+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 todos with optional pagination"""
+    return db.query(Todo).offset(skip).limit(limit).all()
+
+
+def get_todo(db: Session, todo_id: int) -> Optional[Todo]:
+    """Get a single 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.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 a todo"""
+    db_todo = get_todo(db, todo_id)
+    if not db_todo:
+        return None
+
+    # Only update fields that are present in the update schema
+    update_data = todo.model_dump(exclude_unset=True)
+    for key, value in update_data.items():
+        setattr(db_todo, key, value)
+
+    db.add(db_todo)
+    db.commit()
+    db.refresh(db_todo)
+    return db_todo
+
+
+def delete_todo(db: Session, todo_id: int) -> bool:
+    """Delete a todo"""
+    db_todo = get_todo(db, todo_id)
+    if not db_todo:
+        return False
+
+    db.delete(db_todo)
+    db.commit()
+    return True

app/db/base.py

@@ -0,0 +1,5 @@
+from app.db.session import Base
+from app.models.todo import Todo
+
+# Import all models here that should be included in the database
+__all__ = ["Todo", "Base"]

app/db/session.py

@@ -0,0 +1,26 @@
+from sqlalchemy import create_engine
+from sqlalchemy.ext.declarative import declarative_base
+from sqlalchemy.orm import sessionmaker
+
+from app.core.config import settings
+
+# Create engine
+engine = create_engine(
+    settings.SQLALCHEMY_DATABASE_URL,
+    connect_args={"check_same_thread": False},  # SQLite specific
+)
+
+# Create SessionLocal class
+SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
+
+# Create Base class
+Base = declarative_base()
+
+
+def get_db():
+    """Dependency for getting DB session"""
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()

app/models/todo.py

@@ -0,0 +1,19 @@
+from sqlalchemy import Column, Integer, String, Boolean, DateTime, func
+from sqlalchemy.sql import expression
+
+from app.db.session import Base
+
+
+class Todo(Base):
+    """Todo model for database representation"""
+
+    __tablename__ = "todos"
+
+    id = Column(Integer, primary_key=True, index=True)
+    title = Column(String, nullable=False)
+    description = Column(String, nullable=True)
+    completed = Column(Boolean, server_default=expression.false(), nullable=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/schemas/todo.py

@@ -0,0 +1,45 @@
+from datetime import datetime
+from typing import Optional
+
+from pydantic import BaseModel
+
+
+class TodoBase(BaseModel):
+    """Base schema for Todo"""
+
+    title: str
+    description: Optional[str] = None
+    completed: bool = False
+
+
+class TodoCreate(TodoBase):
+    """Schema for creating a new Todo"""
+
+    pass
+
+
+class TodoUpdate(BaseModel):
+    """Schema for updating a Todo (all fields optional)"""
+
+    title: Optional[str] = None
+    description: Optional[str] = None
+    completed: Optional[bool] = None
+
+
+class TodoInDB(TodoBase):
+    """Schema for Todo stored in DB"""
+
+    id: int
+    created_at: datetime
+    updated_at: datetime
+
+    class Config:
+        """Configure pydantic model"""
+
+        from_attributes = True
+
+
+class TodoResponse(TodoInDB):
+    """Schema for Todo response"""
+
+    pass

main.py

@@ -0,0 +1,29 @@
+from fastapi import FastAPI
+from fastapi.middleware.cors import CORSMiddleware
+
+from app.api.routes import todo_router, health_router
+from app.core.config import settings
+
+app = FastAPI(
+    title=settings.PROJECT_NAME,
+    description=settings.PROJECT_DESCRIPTION,
+    version=settings.PROJECT_VERSION,
+)
+
+# CORS configuration
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=settings.CORS_ORIGINS,
+    allow_credentials=True,
+    allow_methods=["*"],
+    allow_headers=["*"],
+)
+
+# Include routers
+app.include_router(health_router, tags=["health"])
+app.include_router(todo_router, prefix="/api/v1", tags=["todos"])
+
+if __name__ == "__main__":
+    import uvicorn
+
+    uvicorn.run("main:app", host="0.0.0.0", port=8000, reload=True)

migrations/env.py

@@ -0,0 +1,95 @@
+import os
+import sys
+from logging.config import fileConfig
+
+from sqlalchemy import engine_from_config
+from sqlalchemy import pool
+
+from alembic import context
+
+# Append the app directory to sys.path
+sys.path.append(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+
+# Import the Base model
+from app.db.base import Base
+from app.core.config import settings
+
+# 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)
+
+# Set the SQLAlchemy URL from settings
+config.set_main_option("sqlalchemy.url", settings.SQLALCHEMY_DATABASE_URL)
+
+# 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() -> 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"},
+        # For SQLite, we need to support column and table alterations
+        render_as_batch=url.startswith("sqlite"),
+    )
+
+    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:
+        # For SQLite, we need to support column and table alterations
+        is_sqlite = connection.dialect.name == "sqlite"
+
+        context.configure(
+            connection=connection,
+            target_metadata=target_metadata,
+            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 +1,26 @@
+"""${message}
+
+Revision ID: ${up_revision}
+Revises: ${down_revision | comma,n}
+Create Date: ${create_date}
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+${imports if imports else ""}
+
+# revision identifiers, used by Alembic.
+revision: str = ${repr(up_revision)}
+down_revision: Union[str, None] = ${repr(down_revision)}
+branch_labels: Union[str, Sequence[str], None] = ${repr(branch_labels)}
+depends_on: Union[str, Sequence[str], None] = ${repr(depends_on)}
+
+
+def upgrade() -> None:
+    ${upgrades if upgrades else "pass"}
+
+
+def downgrade() -> None:
+    ${downgrades if downgrades else "pass"}

migrations/versions/20231031_010000_create_todos_table.py

@@ -0,0 +1,50 @@
+"""create todos table
+
+Revision ID: 20231031_010000
+Revises:
+Create Date: 2023-10-31 01:00:00
+
+"""
+
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision: str = "20231031_010000"
+down_revision: Union[str, None] = None
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = 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(), server_default=sa.text("0"), nullable=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() -> None:
+    op.drop_index(op.f("ix_todos_id"), table_name="todos")
+    op.drop_table("todos")

requirements.txt

@@ -0,0 +1,8 @@
+fastapi>=0.104.0
+uvicorn>=0.24.0
+sqlalchemy>=2.0.23
+alembic>=1.12.1
+pydantic>=2.4.2
+pydantic-settings>=2.0.3
+python-dotenv>=1.0.0
+ruff>=0.1.3