Build simple Todo application with FastAPI and SQLite

- Created REST API for managing todo items
- Implemented SQLite database with SQLAlchemy ORM
- Added Alembic for database migrations
- Added health check endpoint

generated with BackendIM... (backend.im)

README.md

@@ -1,3 +1,83 @@
-# FastAPI Application
+# Simple Todo Application
 
-This is a FastAPI application bootstrapped by BackendIM, the AI-powered backend generation platform.
+A simple Todo API application built with FastAPI and SQLite.
+
+## Features
+
+- RESTful API for managing todo items
+- SQLite database with SQLAlchemy ORM
+- Alembic migrations for database versioning
+- Health check endpoint
+- Swagger UI documentation
+
+## Project Structure
+
+```
+.
+├── alembic.ini
+├── app
+│   ├── api
+│   │   └── routes
+│   │       ├── health.py
+│   │       └── todos.py
+│   ├── db
+│   │   ├── database.py
+│   │   └── init_db.py
+│   ├── models
+│   │   └── todo.py
+│   └── schemas
+│       └── todo.py
+├── main.py
+├── migrations
+│   ├── README
+│   ├── env.py
+│   ├── script.py.mako
+│   └── versions
+│       └── initial_migration.py
+└── requirements.txt
+```
+
+## Installation
+
+1. Clone the repository
+2. Install the dependencies:
+
+```bash
+pip install -r requirements.txt
+```
+
+## Running the Application
+
+```bash
+uvicorn main:app --reload
+```
+
+The application will be available at http://localhost:8000.
+
+API Documentation is available at:
+- Swagger UI: http://localhost:8000/docs
+- ReDoc: http://localhost:8000/redoc
+
+## API Endpoints
+
+### Health Check
+- `GET /health` - Check API health
+
+### Todo Operations
+- `GET /todos` - List all todos
+- `POST /todos` - Create a new todo
+- `GET /todos/{todo_id}` - Get a specific todo
+- `PUT /todos/{todo_id}` - Update a todo
+- `DELETE /todos/{todo_id}` - Delete a todo
+
+## Database
+
+The application uses SQLite with SQLAlchemy ORM. The database file is stored at `/app/storage/db/db.sqlite`.
+
+## Migrations
+
+This project uses Alembic for database migrations. To run migrations:
+
+```bash
+alembic upgrade head
+```

alembic.ini

@@ -0,0 +1,40 @@
+[alembic]
+script_location = migrations
+prepend_sys_path = .
+version_path_separator = os
+
+sqlalchemy.url = driver://user:pass@localhost/dbname
+
+[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 +1,23 @@
+from fastapi import APIRouter, Depends
+from sqlalchemy.orm import Session
+from app.db.database import get_db
+
+router = APIRouter(
+    prefix="/health",
+    tags=["health"]
+)
+
+@router.get("/")
+def health_check(db: Session = Depends(get_db)):
+    # Check if database connection is working by executing a simple query
+    try:
+        db.execute("SELECT 1")
+        db_status = "healthy"
+    except Exception:
+        db_status = "unhealthy"
+    
+    return {
+        "status": "ok",
+        "database": db_status,
+        "api_version": "0.1.0"
+    }

app/api/routes/todos.py

@@ -0,0 +1,56 @@
+from fastapi import APIRouter, Depends, HTTPException, status
+from sqlalchemy.orm import Session
+from typing import List
+
+from app.db.database import get_db
+from app.models.todo import Todo as TodoModel
+from app.schemas.todo import Todo, TodoCreate, TodoUpdate
+
+router = APIRouter(
+    prefix="/todos",
+    tags=["todos"]
+)
+
+@router.post("/", response_model=Todo, status_code=status.HTTP_201_CREATED)
+def create_todo(todo: TodoCreate, db: Session = Depends(get_db)):
+    db_todo = TodoModel(**todo.dict())
+    db.add(db_todo)
+    db.commit()
+    db.refresh(db_todo)
+    return db_todo
+
+@router.get("/", response_model=List[Todo])
+def read_todos(skip: int = 0, limit: int = 100, db: Session = Depends(get_db)):
+    todos = db.query(TodoModel).offset(skip).limit(limit).all()
+    return todos
+
+@router.get("/{todo_id}", response_model=Todo)
+def read_todo(todo_id: int, db: Session = Depends(get_db)):
+    db_todo = db.query(TodoModel).filter(TodoModel.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=Todo)
+def update_todo(todo_id: int, todo: TodoUpdate, db: Session = Depends(get_db)):
+    db_todo = db.query(TodoModel).filter(TodoModel.id == todo_id).first()
+    if db_todo is None:
+        raise HTTPException(status_code=404, detail="Todo not found")
+    
+    update_data = todo.dict(exclude_unset=True)
+    for key, value in update_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)
+def delete_todo(todo_id: int, db: Session = Depends(get_db)):
+    db_todo = db.query(TodoModel).filter(TodoModel.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/db/database.py

@@ -0,0 +1,26 @@
+from pathlib import Path
+from sqlalchemy import create_engine
+from sqlalchemy.ext.declarative import declarative_base
+from sqlalchemy.orm import sessionmaker
+
+# Create database 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()
+
+def get_db():
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()

app/db/init_db.py

@@ -0,0 +1,5 @@
+from app.db.database import engine, Base
+from app.models.todo import Todo
+
+def create_tables():
+    Base.metadata.create_all(bind=engine)

app/models/todo.py

@@ -0,0 +1,13 @@
+from sqlalchemy import Column, Integer, String, Boolean, DateTime
+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, default=func.now())
+    updated_at = Column(DateTime, default=func.now(), onupdate=func.now())

app/schemas/todo.py

@@ -0,0 +1,24 @@
+from pydantic import BaseModel
+from datetime import datetime
+from typing import Optional
+
+class TodoBase(BaseModel):
+    title: str
+    description: Optional[str] = None
+    completed: Optional[bool] = False
+
+class TodoCreate(TodoBase):
+    pass
+
+class TodoUpdate(BaseModel):
+    title: Optional[str] = None
+    description: Optional[str] = None
+    completed: Optional[bool] = None
+
+class Todo(TodoBase):
+    id: int
+    created_at: datetime
+    updated_at: datetime
+
+    class Config:
+        from_attributes = True

main.py

@@ -0,0 +1,20 @@
+from fastapi import FastAPI
+from app.api.routes import todos, health
+from app.db.init_db import create_tables
+
+app = FastAPI(
+    title="Todo API",
+    description="A simple Todo API built with FastAPI and SQLite",
+    version="0.1.0"
+)
+
+@app.on_event("startup")
+async def startup():
+    create_tables()
+
+app.include_router(todos.router)
+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 with Alembic.

migrations/env.py

@@ -0,0 +1,86 @@
+from logging.config import fileConfig
+from pathlib import Path
+
+from sqlalchemy import engine_from_config
+from sqlalchemy import pool
+
+from alembic import context
+
+from app.db.database import Base
+from app.models.todo import Todo
+
+# this is the Alembic Config object, which provides
+# access to the values within the .ini file in use.
+config = context.config
+
+# Override sqlalchemy.url with our database URL
+DB_DIR = Path("/app") / "storage" / "db"
+DB_DIR.mkdir(parents=True, exist_ok=True)
+SQLALCHEMY_DATABASE_URL = f"sqlite:///{DB_DIR}/db.sqlite"
+config.set_main_option("sqlalchemy.url", SQLALCHEMY_DATABASE_URL)
+
+# 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()

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/initial_migration.py

@@ -0,0 +1,36 @@
+"""initial_migration
+
+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('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(), nullable=True),
+        sa.Column('updated_at', sa.DateTime(), 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() -> 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')

requirements.txt

@@ -0,0 +1,6 @@
+fastapi==0.104.0
+uvicorn==0.23.2
+sqlalchemy==2.0.22
+pydantic==2.4.2
+alembic==1.12.1
+python-dotenv==1.0.0