Build Todo application with FastAPI and SQLite

- Set up project structure with FastAPI and SQLAlchemy
- Create Todo model, schemas, and CRUD operations
- Add API endpoints for todo operations (create, read, update, delete)
- Set up Alembic for database migrations
- Add health check endpoint
- Update README with detailed instructions

generated with BackendIM... (backend.im)

README.md

@@ -1,3 +1,111 @@
-# 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, SQLAlchemy, and SQLite.
+
+## Features
+
+- Create, read, update, and delete todo items
+- Filter todos by completion status
+- Pagination support
+- Health check endpoint
+
+## Project Structure
+
+```
+simpletodoapplication/
+├── app/
+│   ├── __init__.py
+│   ├── crud.py         # CRUD operations
+│   ├── database.py     # Database configuration
+│   ├── models.py       # SQLAlchemy models
+│   └── schemas.py      # Pydantic schemas
+├── migrations/         # Alembic migrations
+├── alembic.ini         # Alembic configuration
+├── main.py             # FastAPI application
+└── requirements.txt    # Project dependencies
+```
+
+## Installation
+
+1. Clone the repository
+2. Install dependencies:
+
+```bash
+pip install -r requirements.txt
+```
+
+## Database Setup
+
+The application uses SQLite, and the database will be created automatically at `/app/storage/db/db.sqlite` when the application starts.
+
+## Running the Application
+
+```bash
+uvicorn main:app --reload
+```
+
+The API will be available at http://localhost:8000
+
+## API Documentation
+
+Once the application is running, you can access the API documentation at:
+
+- Swagger UI: http://localhost:8000/docs
+- ReDoc: http://localhost:8000/redoc
+
+## API Endpoints
+
+### Health Check
+
+- `GET /health` - Check if the API is running
+
+### Todo Operations
+
+- `GET /todos/` - List all todos (supports pagination and filtering by completion status)
+- `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
+
+## Example Usage
+
+### Create a Todo
+
+```bash
+curl -X 'POST' \
+  'http://localhost:8000/todos/' \
+  -H 'Content-Type: application/json' \
+  -d '{
+  "title": "Buy groceries",
+  "description": "Milk, bread, eggs"
+}'
+```
+
+### List All Todos
+
+```bash
+curl -X 'GET' 'http://localhost:8000/todos/'
+```
+
+### Get Completed Todos
+
+```bash
+curl -X 'GET' 'http://localhost:8000/todos/?completed=true'
+```
+
+### Update a Todo
+
+```bash
+curl -X 'PUT' \
+  'http://localhost:8000/todos/1' \
+  -H 'Content-Type: application/json' \
+  -d '{
+  "completed": true
+}'
+```
+
+### Delete a Todo
+
+```bash
+curl -X 'DELETE' 'http://localhost:8000/todos/1'
+```

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 = %%(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 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
+
+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/crud.py

@@ -0,0 +1,41 @@
+from sqlalchemy.orm import Session
+from typing import List, Optional
+from . import models, schemas
+
+def get_todo(db: Session, todo_id: int):
+    return db.query(models.Todo).filter(models.Todo.id == todo_id).first()
+
+def get_todos(db: Session, skip: int = 0, limit: int = 100, completed: Optional[bool] = None):
+    query = db.query(models.Todo)
+    
+    if completed is not None:
+        query = query.filter(models.Todo.completed == completed)
+        
+    return query.order_by(models.Todo.created_at.desc()).offset(skip).limit(limit).all()
+
+def create_todo(db: Session, todo: schemas.TodoCreate):
+    db_todo = models.Todo(
+        title=todo.title,
+        description=todo.description
+    )
+    db.add(db_todo)
+    db.commit()
+    db.refresh(db_todo)
+    return db_todo
+
+def update_todo(db: Session, todo_id: int, todo: schemas.TodoUpdate):
+    db_todo = get_todo(db, todo_id)
+    
+    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
+
+def delete_todo(db: Session, todo_id: int):
+    db_todo = get_todo(db, todo_id)
+    db.delete(db_todo)
+    db.commit()
+    return db_todo

app/database.py

@@ -0,0 +1,22 @@
+from sqlalchemy import create_engine
+from sqlalchemy.ext.declarative import declarative_base
+from sqlalchemy.orm import sessionmaker
+from pathlib import Path
+
+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 init_db():
+    from app import models
+    Base.metadata.create_all(bind=engine)

app/models.py

@@ -0,0 +1,14 @@
+from sqlalchemy import Column, Integer, String, Boolean, DateTime, func
+from sqlalchemy.ext.declarative import declarative_base
+from app.database import Base
+import datetime
+
+class Todo(Base):
+    __tablename__ = "todos"
+
+    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, default=datetime.datetime.utcnow)
+    updated_at = Column(DateTime, default=datetime.datetime.utcnow, onupdate=datetime.datetime.utcnow)

app/schemas.py

@@ -0,0 +1,24 @@
+from pydantic import BaseModel, Field
+from typing import Optional
+from datetime import datetime
+
+class TodoBase(BaseModel):
+    title: str = Field(..., max_length=100, example="Buy groceries")
+    description: Optional[str] = Field(None, example="Milk, bread, eggs, cheese")
+
+class TodoCreate(TodoBase):
+    pass
+
+class TodoUpdate(BaseModel):
+    title: Optional[str] = Field(None, max_length=100, example="Buy more groceries")
+    description: Optional[str] = Field(None, example="Update shopping list")
+    completed: Optional[bool] = Field(None, example=True)
+
+class Todo(TodoBase):
+    id: int
+    completed: bool
+    created_at: datetime
+    updated_at: datetime
+
+    class Config:
+        orm_mode = True

main.py

@@ -0,0 +1,60 @@
+import uvicorn
+from fastapi import FastAPI, Depends, HTTPException, status
+from sqlalchemy.orm import Session
+from pathlib import Path
+from typing import List, Optional
+
+from app import models, schemas, crud
+from app.database import SessionLocal, engine, init_db
+
+app = FastAPI(title="Todo Application API", 
+             description="A simple Todo application API built with FastAPI and SQLAlchemy",
+             version="1.0.0")
+
+# Initialize database
+init_db()
+
+# Dependency
+def get_db():
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()
+
+@app.get("/health", status_code=status.HTTP_200_OK)
+def health_check():
+    return {"status": "healthy"}
+
+@app.post("/todos/", response_model=schemas.Todo, status_code=status.HTTP_201_CREATED)
+def create_todo(todo: schemas.TodoCreate, db: Session = Depends(get_db)):
+    return crud.create_todo(db=db, todo=todo)
+
+@app.get("/todos/", response_model=List[schemas.Todo])
+def read_todos(skip: int = 0, limit: int = 100, completed: Optional[bool] = None, db: Session = Depends(get_db)):
+    return crud.get_todos(db=db, skip=skip, limit=limit, completed=completed)
+
+@app.get("/todos/{todo_id}", response_model=schemas.Todo)
+def read_todo(todo_id: int, db: Session = Depends(get_db)):
+    db_todo = crud.get_todo(db=db, todo_id=todo_id)
+    if db_todo is None:
+        raise HTTPException(status_code=404, detail="Todo not found")
+    return db_todo
+
+@app.put("/todos/{todo_id}", response_model=schemas.Todo)
+def update_todo(todo_id: int, todo: schemas.TodoUpdate, db: Session = Depends(get_db)):
+    db_todo = crud.get_todo(db=db, todo_id=todo_id)
+    if db_todo is None:
+        raise HTTPException(status_code=404, detail="Todo not found")
+    return crud.update_todo(db=db, todo_id=todo_id, todo=todo)
+
+@app.delete("/todos/{todo_id}", status_code=status.HTTP_204_NO_CONTENT)
+def delete_todo(todo_id: int, db: Session = Depends(get_db)):
+    db_todo = crud.get_todo(db=db, todo_id=todo_id)
+    if db_todo is None:
+        raise HTTPException(status_code=404, detail="Todo not found")
+    crud.delete_todo(db=db, todo_id=todo_id)
+    return None
+
+if __name__ == "__main__":
+    uvicorn.run("main:app", host="0.0.0.0", port=8000, reload=True)

migrations/README

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

migrations/env.py

@@ -0,0 +1,77 @@
+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 app.database import Base
+from app.models import Todo
+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()

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():
+    ${upgrades if upgrades else "pass"}
+
+
+def downgrade():
+    ${downgrades if downgrades else "pass"}

migrations/versions/20250513_initial_migration.py

@@ -0,0 +1,36 @@
+"""initial migration
+
+Revision ID: 20250513
+Revises: 
+Create Date: 2025-05-13
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = '20250513'
+down_revision = None
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    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(), 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():
+    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==0.104.1
+uvicorn==0.23.2
+sqlalchemy==2.0.23
+pydantic==2.4.2
+alembic==1.12.1
+python-dotenv==1.0.0