Add Todo API implementation

- Set up project structure with FastAPI, SQLAlchemy, and Alembic
- Create Todo model and database operations
- Implement CRUD API endpoints for Todo items
- Configure database migrations
- Add comprehensive documentation

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

README.md

@@ -1,3 +1,80 @@
-# FastAPI Application
+# FastAPI Todo Backend Service
 
-This is a FastAPI application bootstrapped by BackendIM, the AI-powered backend generation platform.
+This is a simple Todo API backend service built with FastAPI, SQLAlchemy, and SQLite.
+
+## Features
+
+- CRUD operations for Todo items
+- API documentation with Swagger UI and ReDoc
+- Database migrations with Alembic
+- SQLite database
+
+## Project Structure
+
+```
+.
+├── alembic/              # Database migrations
+├── app/
+│   ├── api/              # API endpoints
+│   │   └── v1/           # API version 1
+│   ├── core/             # Core application configurations
+│   ├── db/               # Database connection and CRUD operations
+│   ├── models/           # SQLAlchemy models
+│   └── schemas/          # Pydantic schemas for request/response
+├── main.py               # Application entry point
+├── requirements.txt      # Python dependencies
+└── alembic.ini           # Alembic configuration
+```
+
+## Getting Started
+
+1. Clone the repository
+2. Install dependencies:
+```bash
+pip install -r requirements.txt
+```
+3. Run database migrations:
+```bash
+alembic upgrade head
+```
+4. Start the application:
+```bash
+uvicorn main:app --reload
+```
+
+## API Documentation
+
+Once the application is running, you can access:
+- Swagger UI: http://localhost:8000/docs
+- ReDoc: http://localhost:8000/redoc
+
+## API Endpoints
+
+- GET `/api/v1/todos/`: List all todo items
+- POST `/api/v1/todos/`: Create a new todo item
+- GET `/api/v1/todos/{todo_id}`: Get a specific todo item
+- PUT `/api/v1/todos/{todo_id}`: Update a todo item
+- DELETE `/api/v1/todos/{todo_id}`: Delete a todo item
+
+## Example
+
+### Create a new todo
+
+```bash
+curl -X 'POST' \
+  'http://localhost:8000/api/v1/todos/' \
+  -H 'Content-Type: application/json' \
+  -d '{
+  "title": "Buy groceries",
+  "description": "Milk, bread, eggs",
+  "completed": false
+}'
+```
+
+### List all todos
+
+```bash
+curl -X 'GET' \
+  'http://localhost:8000/api/v1/todos/' \
+  -H 'accept: application/json'
+```

alembic.ini

@@ -0,0 +1,102 @@
+# 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
+
+# sys.path path, will be prepended to sys.path if present.
+# defaults to the current working directory.
+prepend_sys_path = .
+
+# timezone to use when rendering the date within the migration file
+# as well as the filename.
+# If specified, requires the python-dateutil library that can be
+# installed by adding `alembic[tz]` to the pip requirements
+# 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.
+# The path separator used here should be the separator specified by "version_path_separator" below.
+# version_locations = %(here)s/bar:%(here)s/bat:alembic/versions
+
+# version path separator; As mentioned above, this is the character used to split
+# version_locations. The default within new alembic.ini files is "os", which uses os.pathsep.
+# If this key is omitted entirely, it falls back to the legacy behavior of splitting on spaces and/or commas.
+# Valid values for version_path_separator are:
+#
+# version_path_separator = :
+# version_path_separator = ;
+# version_path_separator = space
+version_path_separator = os  # Use os.pathsep. Default configuration used for new projects.
+
+# the output encoding used when revision files
+# are written from script.py.mako
+# output_encoding = utf-8
+
+sqlalchemy.url = sqlite:///./todo.db
+
+
+[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 REVISION_SCRIPT_FILENAME
+
+# 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 +1,82 @@
+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
+from app.models.todo import Todo
+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
+config.set_main_option("sqlalchemy.url", settings.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 = 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/2023_11_25_create_todos_table.py

@@ -0,0 +1,36 @@
+"""Create todos table
+
+Revision ID: 2023_11_25_create_todos
+Revises: 
+Create Date: 2023-11-25 12:00:00.000000
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = '2023_11_25_create_todos'
+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=True),
+        sa.Column('description', sa.String(), nullable=True),
+        sa.Column('completed', sa.Boolean(), nullable=True),
+        sa.Column('created_at', sa.DateTime(timezone=True), server_default=sa.text('now()'), 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)
+    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')

app/api/v1/api.py

@@ -0,0 +1,6 @@
+from fastapi import APIRouter
+
+from app.api.v1.endpoints import todos
+
+api_router = APIRouter()
+api_router.include_router(todos.router, prefix="/todos", tags=["todos"])

app/api/v1/endpoints/todos.py

@@ -0,0 +1,86 @@
+from typing import List, Optional
+
+from fastapi import APIRouter, Depends, HTTPException, status
+from sqlalchemy.orm import Session
+
+from app.db.session import get_db
+from app.db import crud
+from app.schemas.todo import Todo, TodoCreate, TodoUpdate
+
+router = APIRouter()
+
+
+@router.get("/", response_model=List[Todo])
+def read_todos(
+    skip: int = 0, 
+    limit: int = 100, 
+    db: Session = Depends(get_db)
+):
+    """
+    Retrieve todos.
+    """
+    todos = crud.get_todos(db, skip=skip, limit=limit)
+    return todos
+
+
+@router.post("/", response_model=Todo, status_code=status.HTTP_201_CREATED)
+def create_todo(
+    todo: TodoCreate, 
+    db: Session = Depends(get_db)
+):
+    """
+    Create a new todo.
+    """
+    return crud.create_todo(db=db, todo=todo)
+
+
+@router.get("/{todo_id}", response_model=Todo)
+def read_todo(
+    todo_id: int, 
+    db: Session = Depends(get_db)
+):
+    """
+    Get a specific todo by id.
+    """
+    db_todo = crud.get_todo(db, todo_id=todo_id)
+    if db_todo is None:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND, 
+            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)
+):
+    """
+    Update a todo.
+    """
+    db_todo = crud.update_todo(db, todo_id=todo_id, todo=todo)
+    if db_todo is None:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND, 
+            detail="Todo not found"
+        )
+    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.
+    """
+    deleted = crud.delete_todo(db, todo_id=todo_id)
+    if not deleted:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND, 
+            detail="Todo not found"
+        )
+    return None

app/core/config.py

@@ -0,0 +1,12 @@
+import os
+from pydantic import BaseSettings
+from dotenv import load_dotenv
+
+load_dotenv()
+
+class Settings(BaseSettings):
+    APP_NAME: str = "Todo API"
+    DATABASE_URL: str = os.getenv("DATABASE_URL", "sqlite:///./todo.db")
+    API_V1_STR: str = "/api/v1"
+
+settings = Settings()

app/db/base.py

@@ -0,0 +1,10 @@
+from sqlalchemy import create_engine
+from sqlalchemy.ext.declarative import declarative_base
+from sqlalchemy.orm import sessionmaker
+
+from app.core.config import settings
+
+engine = create_engine(settings.DATABASE_URL, connect_args={"check_same_thread": False})
+SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
+
+Base = declarative_base()

app/db/crud.py

@@ -0,0 +1,46 @@
+from typing import List, Optional, Dict, Any
+
+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(**todo.dict())
+    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.dict(exclude_unset=True)
+    for field, value in update_data.items():
+        setattr(db_todo, field, value)
+    
+    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/session.py

@@ -0,0 +1,8 @@
+from app.db.base import SessionLocal
+
+def get_db():
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()

app/models/todo.py

@@ -0,0 +1,14 @@
+from sqlalchemy import Column, Integer, String, Boolean, DateTime
+from sqlalchemy.sql import func
+
+from app.db.base 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(timezone=True), server_default=func.now())
+    updated_at = Column(DateTime(timezone=True), onupdate=func.now())

app/schemas/todo.py

@@ -0,0 +1,33 @@
+from datetime import datetime
+from typing import Optional
+
+from pydantic import BaseModel
+
+
+class TodoBase(BaseModel):
+    title: str
+    description: Optional[str] = None
+    completed: bool = False
+
+
+class TodoCreate(TodoBase):
+    pass
+
+
+class TodoUpdate(BaseModel):
+    title: Optional[str] = None
+    description: Optional[str] = None
+    completed: Optional[bool] = None
+
+
+class TodoInDBBase(TodoBase):
+    id: int
+    created_at: datetime
+    updated_at: Optional[datetime] = None
+
+    class Config:
+        orm_mode = True
+
+
+class Todo(TodoInDBBase):
+    pass

main.py

@@ -0,0 +1,34 @@
+import uvicorn
+from fastapi import FastAPI
+from fastapi.middleware.cors import CORSMiddleware
+
+from app.api.v1.api import api_router
+from app.core.config import settings
+from app.db.base import Base, engine
+
+# Create all database tables (if they don't exist)
+Base.metadata.create_all(bind=engine)
+
+app = FastAPI(
+    title=settings.APP_NAME,
+    openapi_url=f"{settings.API_V1_STR}/openapi.json"
+)
+
+# Set all CORS enabled origins
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=["*"],
+    allow_credentials=True,
+    allow_methods=["*"],
+    allow_headers=["*"],
+)
+
+app.include_router(api_router, prefix=settings.API_V1_STR)
+
+@app.get("/")
+def read_root():
+    return {"message": "Welcome to the Todo API!"}
+
+
+if __name__ == "__main__":
+    uvicorn.run("main:app", host="0.0.0.0", port=8000, reload=True)

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