Create Simple Todo Application with FastAPI and SQLite

- Set up project structure and dependencies
- Implement Todo model with SQLAlchemy
- Configure SQLite database connection
- Create Alembic migration scripts
- Implement RESTful API endpoints for CRUD operations
- Add health check endpoint
- Update README with documentation

generated with BackendIM... (backend.im)

README.md

@@ -1,3 +1,109 @@
-# FastAPI Application
+# Simple Todo Application
 
-This is a FastAPI application bootstrapped by BackendIM, the AI-powered backend generation platform.
+A simple Todo application API built with FastAPI and SQLite.
+
+## Features
+
+- Create, read, update, and delete todo items
+- SQLite database with SQLAlchemy ORM
+- Alembic migrations
+- Health check endpoint
+
+## Project Structure
+
+```
+├── alembic/              # Database migrations
+├── app/                  # Application package
+│   ├── api/              # API endpoints
+│   ├── core/             # Core configuration
+│   ├── crud/             # CRUD operations
+│   ├── db/               # Database setup
+│   ├── models/           # SQLAlchemy models
+│   └── schemas/          # Pydantic schemas
+├── alembic.ini           # Alembic configuration
+├── main.py               # FastAPI application
+└── requirements.txt      # Python dependencies
+```
+
+## Installation
+
+1. Clone the repository:
+
+```bash
+git clone https://github.com/yourusername/simpletodoapplication.git
+cd simpletodoapplication
+```
+
+2. Install dependencies:
+
+```bash
+pip install -r requirements.txt
+```
+
+3. Run database migrations:
+
+```bash
+alembic upgrade head
+```
+
+## Usage
+
+Start the application:
+
+```bash
+uvicorn main:app --reload
+```
+
+The application will be available at http://localhost:8000.
+
+API documentation is available at:
+- http://localhost:8000/docs (Swagger UI)
+- http://localhost:8000/redoc (ReDoc)
+
+## API Endpoints
+
+### Todo Endpoints
+
+- `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
+
+### Health Check
+
+- `GET /health` - Check API health
+
+## Example Requests
+
+### Create a Todo
+
+```bash
+curl -X 'POST' \
+  'http://localhost:8000/todos/' \
+  -H 'Content-Type: application/json' \
+  -d '{
+  "title": "Buy groceries",
+  "description": "Milk, eggs, bread",
+  "completed": false
+}'
+```
+
+### List All Todos
+
+```bash
+curl -X 'GET' 'http://localhost:8000/todos/'
+```
+
+### Update a Todo
+
+```bash
+curl -X 'PUT' \
+  'http://localhost:8000/todos/1' \
+  -H 'Content-Type: application/json' \
+  -d '{
+  "title": "Buy groceries",
+  "description": "Milk, eggs, bread, cheese",
+  "completed": true
+}'
+```

alembic.ini

@@ -0,0 +1,85 @@
+# 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 +1,91 @@
+import os
+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 myapp import mymodel
+# target_metadata = mymodel.Base.metadata
+import sys
+sys.path.insert(0, os.path.dirname(os.path.dirname(__file__)))
+
+from app.db.base 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.
+
+from app.core.config import settings
+
+def get_url():
+    return settings.SQLALCHEMY_DATABASE_URL
+
+
+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 = get_url()
+    context.configure(
+        url=url,
+        target_metadata=target_metadata,
+        literal_binds=True,
+        compare_type=True,
+    )
+
+    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.
+
+    """
+    configuration = config.get_section(config.config_ini_section)
+    configuration["sqlalchemy.url"] = get_url()
+    connectable = engine_from_config(
+        configuration,
+        prefix="sqlalchemy.",
+        poolclass=pool.NullPool,
+    )
+
+    with connectable.connect() as connection:
+        context.configure(
+            connection=connection, 
+            target_metadata=target_metadata,
+            compare_type=True,
+        )
+
+        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/01_create_todo_table.py

@@ -0,0 +1,37 @@
+"""create_todo_table
+
+Revision ID: 01_create_todo_table
+Revises: 
+Create Date: 2025-05-13
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = '01_create_todo_table'
+down_revision = None
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    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(), default=False),
+        sa.Column('created_at', sa.DateTime(timezone=True), server_default=sa.text('(CURRENT_TIMESTAMP)')),
+        sa.Column('updated_at', sa.DateTime(timezone=True), onupdate=sa.text('(CURRENT_TIMESTAMP)')),
+        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():
+    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/__init__.py

@@ -0,0 +1 @@
+# App module

app/api/__init__.py

@@ -0,0 +1 @@
+# API module

app/api/deps.py

@@ -0,0 +1 @@
+from app.db.session import get_db

app/api/endpoints/__init__.py

@@ -0,0 +1 @@
+# API endpoints

app/api/endpoints/todos.py

@@ -0,0 +1,87 @@
+from typing import List, Any
+from fastapi import APIRouter, Depends, HTTPException, status
+from sqlalchemy.orm import Session
+
+from app import crud
+from app.api.deps import get_db
+from app.schemas.todo import TodoCreate, TodoResponse, TodoUpdate
+
+router = APIRouter()
+
+@router.get("/", response_model=List[TodoResponse])
+def read_todos(
+    db: Session = Depends(get_db),
+    skip: int = 0,
+    limit: int = 100,
+) -> Any:
+    """
+    Retrieve todos.
+    """
+    todos = crud.todo.get_todos(db=db, skip=skip, limit=limit)
+    return todos
+
+@router.post("/", response_model=TodoResponse, status_code=status.HTTP_201_CREATED)
+def create_todo(
+    *,
+    db: Session = Depends(get_db),
+    todo_in: TodoCreate,
+) -> Any:
+    """
+    Create new todo.
+    """
+    todo = crud.todo.create_todo(db=db, todo=todo_in)
+    return todo
+
+@router.get("/{todo_id}", response_model=TodoResponse)
+def read_todo(
+    *,
+    db: Session = Depends(get_db),
+    todo_id: int,
+) -> Any:
+    """
+    Get todo by ID.
+    """
+    todo = crud.todo.get_todo(db=db, todo_id=todo_id)
+    if not todo:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail="Todo not found"
+        )
+    return todo
+
+@router.put("/{todo_id}", response_model=TodoResponse)
+def update_todo(
+    *,
+    db: Session = Depends(get_db),
+    todo_id: int,
+    todo_in: TodoUpdate,
+) -> Any:
+    """
+    Update a todo.
+    """
+    todo = crud.todo.get_todo(db=db, todo_id=todo_id)
+    if not todo:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail="Todo not found"
+        )
+    todo = crud.todo.update_todo(db=db, todo_id=todo_id, todo=todo_in)
+    return todo
+
+@router.delete("/{todo_id}", status_code=status.HTTP_204_NO_CONTENT)
+def delete_todo(
+    *,
+    db: Session = Depends(get_db),
+    todo_id: int,
+) -> Any:
+    """
+    Delete a todo.
+    """
+    todo = crud.todo.get_todo(db=db, todo_id=todo_id)
+    if not todo:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail="Todo not found"
+        )
+    crud.todo.delete_todo(db=db, todo_id=todo_id)
+    return None

app/api/routes.py

@@ -0,0 +1,6 @@
+from fastapi import APIRouter
+
+from app.api.endpoints import todos
+
+router = APIRouter()
+router.include_router(todos.router, prefix="/todos", tags=["todos"])

app/core/__init__.py

@@ -0,0 +1 @@
+# Core module

app/core/config.py

@@ -0,0 +1,18 @@
+from pathlib import Path
+from pydantic_settings import BaseSettings
+
+class Settings(BaseSettings):
+    PROJECT_NAME: str = "Todo Application"
+    
+    DB_DIR: Path = Path("/app") / "storage" / "db"
+    
+    # This ensures the DB_DIR exists
+    def __init__(self, **kwargs):
+        super().__init__(**kwargs)
+        self.DB_DIR.mkdir(parents=True, exist_ok=True)
+
+    @property
+    def SQLALCHEMY_DATABASE_URL(self) -> str:
+        return f"sqlite:///{self.DB_DIR}/db.sqlite"
+
+settings = Settings()

app/crud/__init__.py

@@ -0,0 +1 @@
+# CRUD module

app/crud/todo.py

@@ -0,0 +1,41 @@
+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_todo(db: Session, todo_id: int) -> Optional[Todo]:
+    return db.query(Todo).filter(Todo.id == todo_id).first()
+
+def get_todos(db: Session, skip: int = 0, limit: int = 100) -> List[Todo]:
+    return db.query(Todo).offset(skip).limit(limit).all()
+
+def create_todo(db: Session, todo: TodoCreate) -> Todo:
+    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
+
+def update_todo(db: Session, todo_id: int, todo: TodoUpdate) -> Optional[Todo]:
+    db_todo = get_todo(db, todo_id)
+    if not db_todo:
+        return None
+    
+    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:
+    db_todo = get_todo(db, todo_id)
+    if not db_todo:
+        return False
+    
+    db.delete(db_todo)
+    db.commit()
+    return True

app/db/__init__.py

@@ -0,0 +1 @@
+# Database module

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  # noqa
+from app.models.todo import Todo  # noqa

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 +1,18 @@
+from sqlalchemy import create_engine
+from sqlalchemy.orm import sessionmaker
+
+from app.core.config import settings
+
+engine = create_engine(
+    settings.SQLALCHEMY_DATABASE_URL,
+    connect_args={"check_same_thread": False}  # Needed for SQLite
+)
+SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
+
+# Dependency
+def get_db():
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()

app/models/__init__.py

@@ -0,0 +1 @@
+# Models module

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), onupdate=func.now())

app/schemas/__init__.py

@@ -0,0 +1 @@
+# Schemas module

app/schemas/todo.py

@@ -0,0 +1,27 @@
+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 to return to client
+class TodoResponse(TodoBase):
+    id: int
+    created_at: datetime
+    updated_at: Optional[datetime] = None
+
+    class Config:
+        from_attributes = True

main.py

@@ -0,0 +1,21 @@
+from fastapi import FastAPI
+from app.api.routes import router as api_router
+from app.core.config import settings
+
+app = FastAPI(
+    title=settings.PROJECT_NAME,
+    description="A simple Todo application API",
+    version="0.1.0",
+    docs_url="/docs",
+    redoc_url="/redoc",
+)
+
+app.include_router(api_router)
+
+@app.get("/health", tags=["health"])
+async def health_check():
+    return {"status": "healthy"}
+
+if __name__ == "__main__":
+    import uvicorn
+    uvicorn.run("main:app", host="0.0.0.0", port=8000, reload=True)

requirements.txt

@@ -0,0 +1,6 @@
+fastapi==0.110.0
+uvicorn==0.27.0
+sqlalchemy==2.0.25
+pydantic==2.6.1
+alembic==1.13.1
+python-dotenv==1.0.0