Create simple todo app with FastAPI and SQLite

- Setup project structure
- Create database models for todos
- Configure SQLite database connection
- Add Alembic migration scripts
- Implement CRUD API endpoints for todos
- Add health check endpoint
- Update README with documentation

generated with BackendIM... (backend.im)

README.md

@@ -1,3 +1,120 @@
-# FastAPI Application
+# Simple Todo App
 
-This is a FastAPI application bootstrapped by BackendIM, the AI-powered backend generation platform.
+A simple REST API for managing todos built with FastAPI and SQLite.
+
+## Features
+
+- Create, read, update, and delete todos
+- SQLite database with SQLAlchemy ORM
+- Database migrations with Alembic
+- Health check endpoint
+- API documentation (Swagger UI and ReDoc)
+
+## Project Structure
+
+```
+simpletodoapp/
+├── alembic/               # Database migration scripts
+│   ├── versions/          # Migration version files
+│   ├── env.py             # Alembic environment configuration
+│   └── script.py.mako     # Migration script template
+├── app/                   # Application package
+│   ├── __init__.py        # Package initializer
+│   ├── database.py        # Database session and engine setup
+│   ├── models.py          # SQLAlchemy ORM models
+│   └── schemas.py         # Pydantic schemas for request/response validation
+├── alembic.ini            # Alembic configuration file
+├── main.py                # Application entry point
+├── README.md              # Project documentation
+└── requirements.txt       # Project dependencies
+```
+
+## Installation
+
+1. Clone the repository:
+
+```bash
+git clone <repository-url>
+cd simpletodoapp
+```
+
+2. Install dependencies:
+
+```bash
+pip install -r requirements.txt
+```
+
+3. Run the application:
+
+```bash
+uvicorn main:app --reload
+```
+
+The application will be available at http://localhost:8000.
+
+## API Documentation
+
+- Swagger UI: http://localhost:8000/docs
+- ReDoc: http://localhost:8000/redoc
+
+## API Endpoints
+
+### Health Check
+
+```
+GET /health
+```
+
+Returns the health status of the application.
+
+### Todos
+
+```
+GET /todos
+```
+
+Returns a list of all todos.
+
+```
+GET /todos/{todo_id}
+```
+
+Returns a specific todo by ID.
+
+```
+POST /todos
+```
+
+Creates a new todo.
+
+Request Body:
+
+```json
+{
+  "title": "Buy groceries",
+  "description": "Milk, eggs, bread",
+  "completed": false
+}
+```
+
+```
+PUT /todos/{todo_id}
+```
+
+Updates an existing todo.
+
+Request Body:
+
+```json
+{
+  "title": "Buy groceries",
+  "description": "Milk, eggs, bread, cheese",
+  "completed": true
+}
+```
+
+```
+DELETE /todos/{todo_id}
+```
+
+Deletes a todo by ID.

alembic.ini

@@ -0,0 +1,84 @@
+# A generic, single database configuration.
+
+[alembic]
+# path to migration scripts
+script_location = alembic
+
+# 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 alembic/versions.  When using multiple version
+# directories, initial revisions must be specified with --version-path
+# version_locations = %(here)s/bar %(here)s/bat alembic/versions
+
+# 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
+
+# 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

alembic/env.py

@@ -0,0 +1,84 @@
+from logging.config import fileConfig
+
+from sqlalchemy import engine_from_config
+from sqlalchemy import pool
+
+from alembic import context
+from app.models import Base
+from pathlib import Path
+
+# this is the Alembic Config object, which provides
+# access to the values within the .ini file in use.
+config = context.config
+
+# Make sure the directory exists
+DB_DIR = Path("/app") / "storage" / "db"
+DB_DIR.mkdir(parents=True, exist_ok=True)
+config.set_main_option("sqlalchemy.url", f"sqlite:///{DB_DIR}/db.sqlite")
+
+# 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 myapp import mymodel
+# target_metadata = mymodel.Base.metadata
+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:
+        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():
+    ${upgrades if upgrades else "pass"}
+
+
+def downgrade():
+    ${downgrades if downgrades else "pass"}

alembic/versions/initial_migration.py

@@ -0,0 +1,36 @@
+"""initial migration
+
+Revision ID: 1a2b3c4d5e6f
+Revises: 
+Create Date: 2025-05-13 10:00:00.000000
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = '1a2b3c4d5e6f'
+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=False),
+        sa.Column('description', sa.String(), nullable=True),
+        sa.Column('completed', sa.Boolean(), nullable=True),
+        sa.Column('created_at', sa.DateTime(timezone=True), 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)
+
+
+def downgrade():
+    op.drop_index(op.f('ix_todos_id'), table_name='todos')
+    op.drop_table('todos')

app/database.py

@@ -0,0 +1,28 @@
+from sqlalchemy import create_engine
+from sqlalchemy.ext.declarative import declarative_base
+from sqlalchemy.orm import sessionmaker
+from pathlib import Path
+
+from app.models import Base
+
+# Create storage directory for SQLite database
+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)
+
+def get_db():
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()
+
+def create_tables():
+    Base.metadata.create_all(bind=engine)

app/models.py

@@ -0,0 +1,15 @@
+from sqlalchemy import Column, Integer, String, Boolean, DateTime
+from sqlalchemy.ext.declarative import declarative_base
+from sqlalchemy.sql import func
+
+Base = declarative_base()
+
+class Todo(Base):
+    __tablename__ = "todos"
+
+    id = Column(Integer, primary_key=True, index=True)
+    title = Column(String, nullable=False)
+    description = Column(String, nullable=True)
+    completed = Column(Boolean, default=False)
+    created_at = Column(DateTime(timezone=True), default=func.now())
+    updated_at = Column(DateTime(timezone=True), default=func.now(), onupdate=func.now())

app/schemas.py

@@ -0,0 +1,22 @@
+from pydantic import BaseModel
+from datetime import datetime
+from typing import Optional
+
+class TodoBase(BaseModel):
+    title: str
+    description: Optional[str] = None
+    completed: bool = False
+
+class TodoCreate(TodoBase):
+    pass
+
+class TodoResponse(TodoBase):
+    id: int
+    created_at: datetime
+    updated_at: datetime
+
+    class Config:
+        from_attributes = True
+
+class HealthResponse(BaseModel):
+    status: str

main.py

@@ -0,0 +1,89 @@
+from fastapi import FastAPI, Depends, HTTPException, status
+from pathlib import Path
+
+from app.database import get_db, create_tables
+from app.models import Todo
+from app.schemas import TodoCreate, TodoResponse, HealthResponse
+from sqlalchemy.orm import Session
+from sqlalchemy.exc import SQLAlchemyError
+from typing import List
+
+app = FastAPI(
+    title="SimpleTodoApp",
+    description="A simple Todo application API",
+    version="0.1.0"
+)
+
+@app.on_event("startup")
+async def startup():
+    create_tables()
+
+@app.get("/health", response_model=HealthResponse)
+async def health_check():
+    return {"status": "healthy"}
+
+@app.post("/todos", response_model=TodoResponse, status_code=status.HTTP_201_CREATED)
+def create_todo(todo: TodoCreate, db: Session = Depends(get_db)):
+    try:
+        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
+    except SQLAlchemyError as e:
+        db.rollback()
+        raise HTTPException(status_code=500, detail=f"Database error: {str(e)}")
+
+@app.get("/todos", response_model=List[TodoResponse])
+def read_todos(skip: int = 0, limit: int = 100, db: Session = Depends(get_db)):
+    try:
+        todos = db.query(Todo).offset(skip).limit(limit).all()
+        return todos
+    except SQLAlchemyError as e:
+        raise HTTPException(status_code=500, detail=f"Database error: {str(e)}")
+
+@app.get("/todos/{todo_id}", response_model=TodoResponse)
+def read_todo(todo_id: int, db: Session = Depends(get_db)):
+    try:
+        todo = db.query(Todo).filter(Todo.id == todo_id).first()
+        if todo is None:
+            raise HTTPException(status_code=404, detail="Todo not found")
+        return todo
+    except SQLAlchemyError as e:
+        raise HTTPException(status_code=500, detail=f"Database error: {str(e)}")
+
+@app.put("/todos/{todo_id}", response_model=TodoResponse)
+def update_todo(todo_id: int, todo: TodoCreate, db: Session = Depends(get_db)):
+    try:
+        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_data = todo.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
+    except SQLAlchemyError as e:
+        db.rollback()
+        raise HTTPException(status_code=500, detail=f"Database error: {str(e)}")
+
+@app.delete("/todos/{todo_id}", status_code=status.HTTP_204_NO_CONTENT)
+def delete_todo(todo_id: int, db: Session = Depends(get_db)):
+    try:
+        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
+    except SQLAlchemyError as e:
+        db.rollback()
+        raise HTTPException(status_code=500, detail=f"Database error: {str(e)}")
+
+if __name__ == "__main__":
+    import uvicorn
+    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
+python-dotenv==1.0.0
+pathlib==1.0.1