Create Todo application with FastAPI and SQLite

- Set up project structure with FastAPI
- Create Todo database model and schema
- Implement database connection with SQLAlchemy
- Set up Alembic migrations
- Implement CRUD API endpoints for Todo items
- Add health check endpoint
- Update documentation in README.md

generated with BackendIM... (backend.im)

README.md

@@ -1,3 +1,83 @@
-# FastAPI Application
+# Todo Application API
 
-This is a FastAPI application bootstrapped by BackendIM, the AI-powered backend generation platform.
+This is a Todo Application API built with FastAPI and SQLite database. It provides CRUD operations for managing todo items.
+
+## Features
+
+- Create, read, update, and delete todo items
+- Filter todos by completion status
+- Health check endpoint
+- SQLite database with SQLAlchemy ORM
+- Alembic migrations
+
+## Project Structure
+
+```
+/
+├── app/
+│   ├── api/
+│   │   ├── health.py       # Health check endpoint
+│   │   └── todos.py        # Todo CRUD endpoints
+│   ├── db/
+│   │   └── database.py     # Database connection
+│   ├── models/
+│   │   └── todo.py         # SQLAlchemy models
+│   ├── schemas/
+│   │   └── todo.py         # Pydantic schemas
+│   └── utils/
+├── migrations/             # Alembic migrations
+│   ├── versions/
+│   │   └── 001_create_todos_table.py
+│   ├── env.py
+│   └── script.py.mako
+├── storage/                # SQLite database location
+│   └── db/
+├── alembic.ini             # Alembic configuration
+├── main.py                 # Application entry point
+├── requirements.txt        # Project dependencies
+└── README.md
+```
+
+## Getting Started
+
+### Prerequisites
+
+- Python 3.7+
+- pip
+
+### 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
+
+Once the server is running, you can access the API documentation at:
+
+- Swagger UI: http://localhost:8000/docs
+- ReDoc: http://localhost:8000/redoc
+
+## API Endpoints
+
+### Todo Endpoints
+
+- `GET /todos`: Get all todo items (with optional filtering)
+- `POST /todos`: Create a new todo item
+- `GET /todos/{todo_id}`: Get a specific todo item
+- `PUT /todos/{todo_id}`: Update a todo item
+- `DELETE /todos/{todo_id}`: Delete a todo item
+
+### Health Endpoint
+
+- `GET /health`: Health check endpoint

alembic.ini

@@ -0,0 +1,84 @@
+# 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:///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/api/health.py

@@ -0,0 +1,22 @@
+from fastapi import APIRouter, Depends
+from sqlalchemy.orm import Session
+from app.db.database import get_db
+
+router = APIRouter()
+
+@router.get("/")
+async def health_check(db: Session = Depends(get_db)):
+    """
+    Health check endpoint to verify the API is running and can connect to the database.
+    """
+    try:
+        # Execute a simple query to check database connection
+        db.execute("SELECT 1")
+        db_status = "healthy"
+    except Exception:
+        db_status = "unhealthy"
+    
+    return {
+        "status": "healthy",
+        "database": db_status
+    }

app/api/todos.py

@@ -0,0 +1,80 @@
+from fastapi import APIRouter, Depends, HTTPException, status, Query
+from sqlalchemy.orm import Session
+from typing import List, Optional
+from app.db.database import get_db
+from app.models.todo import Todo
+from app.schemas.todo import TodoCreate, TodoUpdate, TodoResponse
+
+router = APIRouter()
+
+@router.post("/", response_model=TodoResponse, status_code=status.HTTP_201_CREATED)
+def create_todo(todo: TodoCreate, db: Session = Depends(get_db)):
+    """
+    Create a new todo item.
+    """
+    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
+
+@router.get("/", response_model=List[TodoResponse])
+def read_todos(
+    skip: int = 0, 
+    limit: int = 100, 
+    completed: Optional[bool] = None,
+    db: Session = Depends(get_db)
+):
+    """
+    Get all todo items with optional filtering by completion status.
+    """
+    query = db.query(Todo)
+    if completed is not None:
+        query = query.filter(Todo.completed == completed)
+    
+    todos = query.offset(skip).limit(limit).all()
+    return todos
+
+@router.get("/{todo_id}", response_model=TodoResponse)
+def read_todo(todo_id: int, db: Session = Depends(get_db)):
+    """
+    Get a specific todo item by ID.
+    """
+    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")
+    return db_todo
+
+@router.put("/{todo_id}", response_model=TodoResponse)
+def update_todo(todo_id: int, todo: TodoUpdate, db: Session = Depends(get_db)):
+    """
+    Update a todo item.
+    """
+    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
+
+@router.delete("/{todo_id}", status_code=status.HTTP_204_NO_CONTENT)
+def delete_todo(todo_id: int, db: Session = Depends(get_db)):
+    """
+    Delete a todo item.
+    """
+    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

app/db/database.py

@@ -0,0 +1,45 @@
+from sqlalchemy import create_engine
+from sqlalchemy.ext.declarative import declarative_base
+from sqlalchemy.orm import sessionmaker
+from pathlib import Path
+
+# 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"
+
+# For local development, use a relative path
+LOCAL_DB_PATH = Path(__file__).parent.parent.parent / "storage" / "db"
+LOCAL_DB_PATH.mkdir(parents=True, exist_ok=True)
+LOCAL_DB_URL = f"sqlite:///{LOCAL_DB_PATH}/db.sqlite"
+
+# Choose the appropriate URL based on environment
+DATABASE_URL = LOCAL_DB_URL  # Default to local development
+
+engine = create_engine(
+    DATABASE_URL,
+    connect_args={"check_same_thread": False}
+)
+
+SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
+
+Base = declarative_base()
+
+def get_db():
+    """
+    Dependency function to get a database session.
+    Used as a FastAPI dependency in route handlers.
+    """
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()
+
+def create_db_and_tables():
+    """
+    Create database tables if they don't exist.
+    Call this function on application startup.
+    """
+    Base.metadata.create_all(bind=engine)

app/models/__init__.py

@@ -0,0 +1 @@
+from app.models.todo import Todo

app/models/todo.py

@@ -0,0 +1,16 @@
+from sqlalchemy import Column, Integer, String, Boolean, DateTime, func
+from sqlalchemy.ext.declarative import declarative_base
+from app.db.database import Base
+
+class Todo(Base):
+    """
+    Todo model for storing todo items in the database.
+    """
+    __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(timezone=True), server_default=func.now())
+    updated_at = Column(DateTime(timezone=True), server_default=func.now(), onupdate=func.now())

app/schemas/__init__.py

@@ -0,0 +1 @@
+from app.schemas.todo import TodoBase, TodoCreate, TodoUpdate, TodoResponse

app/schemas/todo.py

@@ -0,0 +1,37 @@
+from pydantic import BaseModel, Field
+from typing import Optional
+from datetime import datetime
+
+class TodoBase(BaseModel):
+    """
+    Base schema for Todo items with common attributes.
+    """
+    title: str = Field(..., min_length=1, max_length=100, description="Title of the todo item")
+    description: Optional[str] = Field(None, max_length=500, description="Detailed description of the todo item")
+    completed: bool = Field(False, description="Whether the todo item has been completed")
+
+class TodoCreate(TodoBase):
+    """
+    Schema for creating new Todo items.
+    """
+    pass
+
+class TodoUpdate(BaseModel):
+    """
+    Schema for updating existing Todo items.
+    All fields are optional to allow partial updates.
+    """
+    title: Optional[str] = Field(None, min_length=1, max_length=100, description="Title of the todo item")
+    description: Optional[str] = Field(None, max_length=500, description="Detailed description of the todo item")
+    completed: Optional[bool] = Field(None, description="Whether the todo item has been completed")
+
+class TodoResponse(TodoBase):
+    """
+    Schema for returning Todo items in API responses.
+    """
+    id: int
+    created_at: datetime
+    updated_at: datetime
+
+    class Config:
+        from_attributes = True

main.py

@@ -0,0 +1,35 @@
+from fastapi import FastAPI
+from fastapi.middleware.cors import CORSMiddleware
+from pathlib import Path
+
+from app.db.database import create_db_and_tables
+from app.api.todos import router as todos_router
+from app.api.health import router as health_router
+
+app = FastAPI(
+    title="Todo Application API",
+    description="A simple Todo application API built with FastAPI",
+    version="0.1.0"
+)
+
+# Add CORS middleware
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=["*"],
+    allow_credentials=True,
+    allow_methods=["*"],
+    allow_headers=["*"],
+)
+
+# Include routers
+app.include_router(todos_router, prefix="/todos", tags=["todos"])
+app.include_router(health_router, prefix="/health", tags=["health"])
+
+@app.on_event("startup")
+async def startup():
+    # Create database tables on startup
+    create_db_and_tables()
+
+if __name__ == "__main__":
+    import uvicorn
+    uvicorn.run("main:app", host="0.0.0.0", port=8000, reload=True)

migrations/env.py

@@ -0,0 +1,82 @@
+from logging.config import fileConfig
+
+from sqlalchemy import engine_from_config
+from sqlalchemy import pool
+
+from alembic import context
+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
+
+# 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.db.database import Base
+from app.models.todo 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 get_url():
+    # Override with local development path for migrations
+    return f"sqlite:///{Path.cwd() / 'storage' / 'db' / 'db.sqlite'}"
+
+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,
+        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.
+
+    """
+    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
+        )
+
+        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/001_create_todos_table.py

@@ -0,0 +1,36 @@
+"""create todos table
+
+Revision ID: 001
+Revises: 
+Create Date: 2025-05-12
+
+"""
+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():
+    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=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_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