Implement complete Todo API with CRUD endpoints

- Created FastAPI application with Todo CRUD operations
- Implemented GET /api/v1/todos/ for listing todos with pagination
- Implemented POST /api/v1/todos/ for creating new todos
- Implemented GET /api/v1/todos/{id} for retrieving specific todos
- Implemented PUT /api/v1/todos/{id} for updating todos
- Implemented DELETE /api/v1/todos/{id} for deleting todos
- Added proper error handling with 404 responses
- Configured SQLAlchemy with SQLite database
- Set up Alembic for database migrations
- Added Pydantic schemas for request/response validation
- Enabled CORS for all origins
- Added health check endpoint at /health
- Updated README with complete API documentation

README.md

@@ -1,3 +1,89 @@
-# FastAPI Application
+# Todo API
 
-This is a FastAPI application bootstrapped by BackendIM, the AI-powered backend generation platform.
+A simple Todo API built with FastAPI, SQLAlchemy, and SQLite.
+
+## Features
+
+- Full CRUD operations for todos
+- RESTful API design
+- Automatic API documentation with Swagger/OpenAPI
+- SQLite database with SQLAlchemy ORM
+- Database migrations with Alembic
+- CORS enabled for all origins
+- Health check endpoint
+
+## API Endpoints
+
+### Base Endpoints
+
+- `GET /` - Root endpoint with API information
+- `GET /health` - Health check endpoint
+- `GET /docs` - Swagger UI documentation
+- `GET /redoc` - ReDoc documentation
+
+### Todo Endpoints
+
+All todo endpoints are prefixed with `/api/v1/todos`
+
+- `GET /api/v1/todos/` - List all todos (with pagination)
+  - Query parameters: `skip` (default: 0), `limit` (default: 100)
+- `POST /api/v1/todos/` - Create a new todo
+- `GET /api/v1/todos/{todo_id}` - Get a specific todo by ID
+- `PUT /api/v1/todos/{todo_id}` - Update a todo by ID
+- `DELETE /api/v1/todos/{todo_id}` - Delete a todo by ID
+
+## Data Model
+
+Each todo has the following fields:
+
+- `id` (integer) - Unique identifier
+- `title` (string, required) - Todo title (1-200 characters)
+- `description` (string, optional) - Todo description (max 1000 characters)
+- `completed` (boolean) - Completion status (default: false)
+- `created_at` (datetime) - Creation timestamp
+- `updated_at` (datetime) - Last update timestamp
+
+## Quick Start
+
+1. Install dependencies:
+   ```bash
+   pip install -r requirements.txt
+   ```
+
+2. Start the application:
+   ```bash
+   uvicorn main:app --reload
+   ```
+
+3. The API will be available at `http://localhost:8000`
+   - API documentation: `http://localhost:8000/docs`
+   - Alternative docs: `http://localhost:8000/redoc`
+
+## Database
+
+The application uses SQLite with the database file stored at `/app/storage/db/db.sqlite`. Database tables are automatically created when the application starts.
+
+## Project Structure
+
+```
+/
+├── main.py                 # FastAPI application entry point
+├── requirements.txt        # Python dependencies
+├── alembic.ini            # Alembic configuration
+├── alembic/               # Database migrations
+├── app/
+│   ├── __init__.py
+│   ├── api/               # API routes
+│   │   ├── __init__.py
+│   │   └── todos.py       # Todo CRUD endpoints
+│   ├── db/                # Database configuration
+│   │   ├── __init__.py
+│   │   ├── base.py        # SQLAlchemy Base
+│   │   └── session.py     # Database session management
+│   ├── models/            # SQLAlchemy models
+│   │   ├── __init__.py
+│   │   └── todo.py        # Todo model
+│   └── schemas/           # Pydantic schemas
+│       ├── __init__.py
+│       └── todo.py        # Todo request/response schemas
+```

alembic.ini

@@ -0,0 +1,96 @@
+# A generic, single database configuration.
+
+[alembic]
+# path to migration scripts
+script_location = alembic
+
+# template used to generate migration file names; The default value is %%(rev)s_%%(slug)s
+# Uncomment the line below if you want the files to be prepended with date and time
+# file_template = %%(year)d_%%(month).2d_%%(day).2d_%%(hour).2d%%(minute).2d-%%(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 number format
+version_num_format = %(migration_id)s_%(slug)s
+
+# version path separator; As mentioned above, this is the character used to split
+# version_locations. The default within new alembic.ini files is "space", for backward
+# compatibility. If using multiple databases, please set to ":" or some other character
+# that isn't a space
+version_path_separator = :
+
+# 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 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/README

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

alembic/env.py

@@ -0,0 +1,83 @@
+from logging.config import fileConfig
+from sqlalchemy import engine_from_config
+from sqlalchemy import pool
+from alembic import context
+import sys
+import os
+
+# Add the project root directory to the Python path
+sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+
+# Import your models here
+from app.db.base import Base
+from app.models.todo import Todo
+
+# 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.
+if config.config_file_name is not None:
+    fileConfig(config.config_file_name)
+
+# add your model's MetaData object here
+# for 'autogenerate' support
+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() -> None:
+    """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() -> None:
+    """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() -> None:
+    ${upgrades if upgrades else "pass"}
+
+
+def downgrade() -> None:
+    ${downgrades if downgrades else "pass"}

alembic/versions/001_initial_migration.py

@@ -0,0 +1,38 @@
+"""Initial migration
+
+Revision ID: 001
+Revises: 
+Create Date: 2024-01-01 12:00:00.000000
+
+"""
+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() -> None:
+    # ### commands auto generated by Alembic - please adjust! ###
+    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),
+    sa.Column('created_at', sa.DateTime(timezone=True), server_default=sa.text('(CURRENT_TIMESTAMP)'), 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)
+    # ### end Alembic commands ###
+
+
+def downgrade() -> None:
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.drop_index(op.f('ix_todos_id'), table_name='todos')
+    op.drop_table('todos')
+    # ### end Alembic commands ###

alembic/versions/__init__.py

@@ -0,0 +1 @@
+# Alembic versions package

app/api/__init__.py

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

app/api/todos.py

@@ -0,0 +1,88 @@
+from fastapi import APIRouter, Depends, HTTPException, status
+from sqlalchemy.orm import Session
+from typing import List
+
+from app.db.session import get_db
+from app.models.todo import Todo
+from app.schemas.todo import TodoCreate, TodoUpdate, TodoResponse
+
+router = APIRouter(prefix="/todos", tags=["todos"])
+
+
+@router.get("/", response_model=List[TodoResponse])
+def get_todos(skip: int = 0, limit: int = 100, db: Session = Depends(get_db)):
+    """
+    Retrieve all todos with optional pagination.
+    """
+    todos = db.query(Todo).offset(skip).limit(limit).all()
+    return todos
+
+
+@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("/{todo_id}", response_model=TodoResponse)
+def get_todo(todo_id: int, db: Session = Depends(get_db)):
+    """
+    Retrieve a specific todo by ID.
+    """
+    todo = db.query(Todo).filter(Todo.id == todo_id).first()
+    if todo is None:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail=f"Todo with id {todo_id} not found"
+        )
+    return todo
+
+
+@router.put("/{todo_id}", response_model=TodoResponse)
+def update_todo(todo_id: int, todo_update: TodoUpdate, db: Session = Depends(get_db)):
+    """
+    Update a specific todo by ID.
+    """
+    todo = db.query(Todo).filter(Todo.id == todo_id).first()
+    if todo is None:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail=f"Todo with id {todo_id} not found"
+        )
+    
+    # Update only the fields that are provided
+    update_data = todo_update.model_dump(exclude_unset=True)
+    
+    for field, value in update_data.items():
+        setattr(todo, field, value)
+    
+    db.commit()
+    db.refresh(todo)
+    return 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 specific todo by ID.
+    """
+    todo = db.query(Todo).filter(Todo.id == todo_id).first()
+    if todo is None:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail=f"Todo with id {todo_id} not found"
+        )
+    
+    db.delete(todo)
+    db.commit()
+    return None

app/db/session.py

@@ -2,9 +2,7 @@ from pathlib import Path
 from sqlalchemy import create_engine
 from sqlalchemy.orm import sessionmaker
 
-from .base import Base
-
-# Database setup with absolute path as specified in guidelines
+# Database directory setup
 DB_DIR = Path("/app") / "storage" / "db"
 DB_DIR.mkdir(parents=True, exist_ok=True)
 
@@ -17,11 +15,9 @@ engine = create_engine(
 
 SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
 
-# Create tables
-Base.metadata.create_all(bind=engine)
 
-# Dependency to get database session
 def get_db():
+    """Dependency to get database session"""
     db = SessionLocal()
     try:
         yield db

app/schemas/__init__.py

@@ -1 +1,3 @@
-# Schemas package
+from .todo import TodoBase, TodoCreate, TodoUpdate, TodoResponse
+
+__all__ = ["TodoBase", "TodoCreate", "TodoUpdate", "TodoResponse"]

app/schemas/todo.py

@@ -1,26 +1,28 @@
-from datetime import datetime
+from pydantic import BaseModel, Field
 from typing import Optional
-from pydantic import BaseModel
+from datetime import datetime
 
 
-class TodoCreate(BaseModel):
-    title: str
-    description: Optional[str] = None
+class TodoBase(BaseModel):
+    title: str = Field(..., min_length=1, max_length=200)
+    description: Optional[str] = Field(None, max_length=1000)
+    completed: bool = False
+
+
+class TodoCreate(TodoBase):
+    pass
 
 
 class TodoUpdate(BaseModel):
-    title: Optional[str] = None
-    description: Optional[str] = None
+    title: Optional[str] = Field(None, min_length=1, max_length=200)
+    description: Optional[str] = Field(None, max_length=1000)
     completed: Optional[bool] = None
 
 
-class TodoResponse(BaseModel):
+class TodoResponse(TodoBase):
     id: int
-    title: str
-    description: Optional[str] = None
-    completed: bool
     created_at: datetime
-    updated_at: datetime
+    updated_at: Optional[datetime] = None
     
     class Config:
         from_attributes = True

main.py

@@ -1,16 +1,20 @@
 from fastapi import FastAPI
 from fastapi.middleware.cors import CORSMiddleware
+from app.api.todos import router as todos_router
+from app.db.base import Base
+from app.db.session import engine
+
+# Create database tables
+Base.metadata.create_all(bind=engine)
 
 app = FastAPI(
-    title="Todo App API",
-    description="A simple Todo application API built with FastAPI",
+    title="Todo API",
+    description="A simple Todo API built with FastAPI",
     version="1.0.0",
-    openapi_url="/openapi.json",
-    docs_url="/docs",
-    redoc_url="/redoc"
+    openapi_url="/openapi.json"
 )
 
-# Configure CORS
+# Add CORS middleware
 app.add_middleware(
     CORSMiddleware,
     allow_origins=["*"],
@@ -19,13 +23,18 @@ app.add_middleware(
     allow_headers=["*"],
 )
 
+# Include routers
+app.include_router(todos_router, prefix="/api/v1")
+
 
 @app.get("/")
-async def root():
-    """Base endpoint that returns app information"""
+def root():
+    """
+    Root endpoint that returns basic information about the API.
+    """
     return {
-        "title": "Todo App API",
-        "description": "A simple Todo application API built with FastAPI",
+        "title": "Todo API",
+        "description": "A simple Todo API built with FastAPI",
         "version": "1.0.0",
         "documentation": "/docs",
         "health_check": "/health"
@@ -33,11 +42,11 @@ async def root():
 
 
 @app.get("/health")
-async def health_check():
-    """Health check endpoint"""
-    return {"status": "healthy", "message": "Todo App API is running"}
-
-
-if __name__ == "__main__":
-    import uvicorn
-    uvicorn.run(app, host="0.0.0.0", port=8000)
+def health_check():
+    """
+    Health check endpoint to verify the application is running.
+    """
+    return {
+        "status": "healthy",
+        "message": "Todo API is running successfully"
+    }