Add Simple Todo Application with FastAPI and SQLite

- Create project structure with FastAPI setup
- Implement Todo model with SQLAlchemy
- Set up database migrations with Alembic
- Create CRUD API endpoints for Todo items
- Add health endpoint for application monitoring
- Update README with documentation

generated with BackendIM... (backend.im)

README.md

@@ -1,3 +1,59 @@
-# FastAPI Application
+# Simple Todo Application
 
-This is a FastAPI application bootstrapped by BackendIM, the AI-powered backend generation platform.
+A RESTful API for a Todo application built with FastAPI and SQLite.
+
+## Features
+
+- Create, Read, Update, and Delete Todo items
+- Health endpoint for application monitoring
+- SQLite database with SQLAlchemy ORM
+- Database migrations with Alembic
+
+## API Endpoints
+
+- **GET /health**: Check application health
+- **GET /api/v1/todos**: List all todos
+- **POST /api/v1/todos**: Create a new todo
+- **GET /api/v1/todos/{id}**: Get a specific todo by ID
+- **PUT /api/v1/todos/{id}**: Update a todo
+- **DELETE /api/v1/todos/{id}**: Delete a todo
+
+## Getting Started
+
+### Prerequisites
+
+- Python 3.8 or higher
+- FastAPI
+- SQLAlchemy
+- Alembic
+
+### Installation
+
+1. Clone the repository
+2. Install dependencies: `pip install -r requirements.txt`
+3. Run database migrations: `alembic upgrade head`
+4. Start the server: `uvicorn main:app --reload`
+
+### API Documentation
+
+API documentation is automatically generated and available at:
+
+- Swagger UI: [http://localhost:8000/docs](http://localhost:8000/docs)
+- ReDoc: [http://localhost:8000/redoc](http://localhost:8000/redoc)
+
+## Project Structure
+
+```
+.
+├── alembic/              # Database migration files
+├── app/                  # Application package
+│   ├── api/              # API routes
+│   │   └── endpoints/    # API endpoint modules
+│   ├── core/             # Core functionality
+│   ├── db/               # Database setup
+│   ├── models/           # SQLAlchemy models
+│   └── schemas/          # Pydantic schemas
+├── main.py               # Application entry point
+├── alembic.ini           # Alembic configuration
+└── requirements.txt      # Project dependencies
+```

alembic.ini

@@ -0,0 +1,40 @@
+[alembic]
+script_location = alembic
+prepend_sys_path = .
+version_path_separator = os
+
+sqlalchemy.url = sqlite:///app/storage/db/db.sqlite
+
+[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

alembic/README

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

alembic/env.py

@@ -0,0 +1,78 @@
+from logging.config import fileConfig
+
+from sqlalchemy import engine_from_config
+from sqlalchemy import pool
+
+from alembic import context
+
+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)
+
+# 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"},
+    )
+
+    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:
+        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()

alembic/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"}

alembic/versions/001_create_todo_table.py

@@ -0,0 +1,37 @@
+"""create todo table
+
+Revision ID: 001
+Revises: 
+Create Date: 2025-05-13
+
+"""
+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() -> None:
+    op.create_table(
+        'todo',
+        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), server_default=sa.text('(CURRENT_TIMESTAMP)'), nullable=False),
+        sa.Column('updated_at', sa.DateTime(timezone=True), server_default=sa.text('(CURRENT_TIMESTAMP)'), nullable=False),
+        sa.PrimaryKeyConstraint('id')
+    )
+    op.create_index(op.f('ix_todo_id'), 'todo', ['id'], unique=False)
+    op.create_index(op.f('ix_todo_title'), 'todo', ['title'], unique=False)
+
+
+def downgrade() -> None:
+    op.drop_index(op.f('ix_todo_title'), table_name='todo')
+    op.drop_index(op.f('ix_todo_id'), table_name='todo')
+    op.drop_table('todo')

app/api/endpoints/todos.py

@@ -0,0 +1,103 @@
+from typing import Any, List
+from fastapi import APIRouter, Depends, HTTPException, status
+from sqlalchemy.orm import Session
+
+from app import schemas
+from app.models.todo import Todo
+from app.db.session import get_db
+
+router = APIRouter()
+
+@router.get("/", response_model=List[schemas.Todo])
+def read_todos(
+    db: Session = Depends(get_db),
+    skip: int = 0,
+    limit: int = 100,
+) -> Any:
+    """
+    Retrieve todos.
+    """
+    todos = db.query(Todo).order_by(Todo.created_at.desc()).offset(skip).limit(limit).all()
+    return todos
+
+@router.post("/", response_model=schemas.Todo, status_code=status.HTTP_201_CREATED)
+def create_todo(
+    *,
+    db: Session = Depends(get_db),
+    todo_in: schemas.TodoCreate,
+) -> Any:
+    """
+    Create new todo.
+    """
+    todo = Todo(
+        title=todo_in.title,
+        description=todo_in.description,
+        completed=todo_in.completed,
+    )
+    db.add(todo)
+    db.commit()
+    db.refresh(todo)
+    return todo
+
+@router.get("/{id}", response_model=schemas.Todo)
+def read_todo(
+    *,
+    db: Session = Depends(get_db),
+    id: int,
+) -> Any:
+    """
+    Get todo by ID.
+    """
+    todo = db.query(Todo).filter(Todo.id == id).first()
+    if not todo:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail=f"Todo with ID {id} not found"
+        )
+    return todo
+
+@router.put("/{id}", response_model=schemas.Todo)
+def update_todo(
+    *,
+    db: Session = Depends(get_db),
+    id: int,
+    todo_in: schemas.TodoUpdate,
+) -> Any:
+    """
+    Update a todo.
+    """
+    todo = db.query(Todo).filter(Todo.id == id).first()
+    if not todo:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail=f"Todo with ID {id} not found"
+        )
+    
+    update_data = todo_in.model_dump(exclude_unset=True)
+    for field, value in update_data.items():
+        setattr(todo, field, value)
+    
+    db.add(todo)
+    db.commit()
+    db.refresh(todo)
+    return todo
+
+@router.delete("/{id}", status_code=status.HTTP_204_NO_CONTENT)
+def delete_todo(
+    *,
+    db: Session = Depends(get_db),
+    id: int,
+) -> Any:
+    """
+    Delete a todo.
+    """
+    todo = db.query(Todo).filter(Todo.id == id).first()
+    if not todo:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail=f"Todo with ID {id} not found"
+        )
+    
+    db.delete(todo)
+    db.commit()
+    return None

app/api/routes.py

@@ -0,0 +1,5 @@
+from fastapi import APIRouter
+from app.api.endpoints import todos
+
+api_router = APIRouter()
+api_router.include_router(todos.router, prefix="/todos", tags=["todos"])

app/core/config.py

@@ -0,0 +1,17 @@
+from pydantic_settings import BaseSettings
+from pathlib import Path
+
+class Settings(BaseSettings):
+    API_V1_STR: str = "/api/v1"
+    PROJECT_NAME: str = "Simple Todo Application"
+    PROJECT_DESCRIPTION: str = "A simple todo application API built with FastAPI and SQLAlchemy"
+    VERSION: str = "1.0.0"
+    
+    # Database settings
+    DB_DIR: Path = Path("/app") / "storage" / "db"
+    
+    class Config:
+        env_file = ".env"
+        case_sensitive = True
+
+settings = Settings()

app/db/base.py

@@ -0,0 +1,4 @@
+# Import all the models, so that Base has them before being
+# imported by Alembic
+from app.db.base_class import Base
+from app.models.todo import Todo

app/db/base_class.py

@@ -0,0 +1,12 @@
+from typing import Any
+from sqlalchemy.ext.declarative import as_declarative, declared_attr
+
+@as_declarative()
+class Base:
+    id: Any
+    __name__: str
+    
+    # Generate __tablename__ automatically
+    @declared_attr
+    def __tablename__(cls) -> str:
+        return cls.__name__.lower()

app/db/session.py

@@ -0,0 +1,23 @@
+from sqlalchemy import create_engine
+from sqlalchemy.orm import sessionmaker
+
+from app.core.config import settings
+
+# Create database directory if it doesn't exist
+settings.DB_DIR.mkdir(parents=True, exist_ok=True)
+
+SQLALCHEMY_DATABASE_URL = f"sqlite:///{settings.DB_DIR}/db.sqlite"
+
+engine = create_engine(
+    SQLALCHEMY_DATABASE_URL,
+    connect_args={"check_same_thread": False}
+)
+
+SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
+
+def get_db():
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()

app/models/todo.py

@@ -0,0 +1,12 @@
+from sqlalchemy import Column, Integer, String, Boolean, DateTime
+from sqlalchemy.sql import func
+
+from app.db.base_class import Base
+
+class Todo(Base):
+    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), server_default=func.now())
+    updated_at = Column(DateTime(timezone=True), server_default=func.now(), onupdate=func.now())

app/schemas/todo.py

@@ -0,0 +1,31 @@
+from pydantic import BaseModel
+from datetime import datetime
+from typing import Optional
+
+# Shared properties
+class TodoBase(BaseModel):
+    title: str
+    description: Optional[str] = None
+    completed: bool = False
+
+# Properties to receive on creation
+class TodoCreate(TodoBase):
+    pass
+
+# Properties to receive on update
+class TodoUpdate(TodoBase):
+    title: Optional[str] = None
+    completed: Optional[bool] = None
+
+# Properties shared by models stored in DB
+class TodoInDBBase(TodoBase):
+    id: int
+    created_at: datetime
+    updated_at: datetime
+
+    class Config:
+        from_attributes = True
+
+# Properties to return to client
+class Todo(TodoInDBBase):
+    pass

main.py

@@ -0,0 +1,26 @@
+from fastapi import FastAPI
+import uvicorn
+from pathlib import Path
+from app.api.routes import api_router
+from app.core.config import settings
+
+app = FastAPI(
+    title=settings.PROJECT_NAME,
+    description=settings.PROJECT_DESCRIPTION,
+    version=settings.VERSION,
+    openapi_url=f"{settings.API_V1_STR}/openapi.json",
+    docs_url="/docs",
+    redoc_url="/redoc",
+)
+
+app.include_router(api_router, prefix=settings.API_V1_STR)
+
+@app.get("/health", tags=["health"])
+def health_check():
+    """
+    Health check endpoint to verify the application is running.
+    """
+    return {"status": "ok", "message": "Application is running"}
+
+if __name__ == "__main__":
+    uvicorn.run("main:app", host="0.0.0.0", port=8000, reload=True)

requirements.txt

@@ -0,0 +1,7 @@
+fastapi==0.103.1
+uvicorn==0.23.2
+sqlalchemy==2.0.20
+alembic==1.12.0
+pydantic==2.3.0
+pydantic-settings==2.0.3
+python-dotenv==1.0.0