Create Todo API with FastAPI and SQLite

- Implement Todo CRUD API endpoints
- Set up SQLite database with SQLAlchemy
- Create Todo model and schemas
- Configure Alembic migrations
- Add comprehensive documentation

🤖 Generated with and Co-Authored by [BackendIM](https://backend.im)

README.md

@@ -1,3 +1,87 @@
-# FastAPI Application
+# Todo Backend Service API
 
-This is a FastAPI application bootstrapped by BackendIM, the AI-powered backend generation platform.
+This is a RESTful API for a Todo application built with FastAPI and SQLite. The API allows users to create, read, update, and delete todo items.
+
+## Features
+
+- CRUD operations for todo items
+- Filtering todos by completion status
+- SQLite database with SQLAlchemy ORM
+- Alembic migrations
+- API documentation with Swagger UI and ReDoc
+
+## Project Structure
+
+```
+todobackendservice/
+├── alembic/             # Database migrations
+├── app/                 # Application package
+│   ├── api/             # API endpoints
+│   ├── core/            # Core functionality, configs
+│   ├── db/              # Database session, dependencies
+│   ├── models/          # SQLAlchemy models
+│   ├── schemas/         # Pydantic schemas
+│   └── storage/         # Storage directory for SQLite
+├── main.py              # Application entry point
+├── alembic.ini          # Alembic configuration
+└── requirements.txt     # Project dependencies
+```
+
+## Getting Started
+
+### Prerequisites
+
+- Python 3.8 or higher
+- pip (Python package installer)
+
+### Installation
+
+1. Clone the repository:
+
+```bash
+git clone <repository-url>
+cd todobackendservice
+```
+
+2. Install the dependencies:
+
+```bash
+pip install -r requirements.txt
+```
+
+3. Run the database migrations:
+
+```bash
+alembic upgrade head
+```
+
+4. Start the application:
+
+```bash
+uvicorn main:app --reload
+```
+
+The API will be available at `http://localhost:8000`.
+
+## API Documentation
+
+The API documentation is available at:
+
+- Swagger UI: `http://localhost:8000/docs`
+- ReDoc: `http://localhost:8000/redoc`
+
+## API Endpoints
+
+### Todos
+
+- `GET /api/v1/todos` - List all todos
+- `POST /api/v1/todos` - Create a new todo
+- `GET /api/v1/todos/{todo_id}` - Get a specific todo
+- `PUT /api/v1/todos/{todo_id}` - Update a todo
+- `DELETE /api/v1/todos/{todo_id}` - Delete a todo
+
+### Query Parameters
+
+- `skip` - Number of records to skip (default: 0)
+- `limit` - Maximum number of records to return (default: 100)
+- `completed` - Filter by completion status (optional)

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:///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/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.
+if config.config_file_name is not None:
+    fileConfig(config.config_file_name)
+
+# add your model's MetaData object here
+# for 'autogenerate' support
+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.
+
+
+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/1182660_create_todo_table.py

@@ -0,0 +1,35 @@
+"""create todo table
+
+Revision ID: 1182660
+Revises: 
+Create Date: 2025-05-11
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = '1182660'
+down_revision = None
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.create_table(
+        'todo',
+        sa.Column('id', sa.Integer(), nullable=False),
+        sa.Column('title', sa.String(length=100), nullable=False),
+        sa.Column('description', sa.Text(), nullable=True),
+        sa.Column('completed', sa.Boolean(), default=False),
+        sa.Column('created_at', sa.DateTime(), default=sa.func.now()),
+        sa.Column('updated_at', sa.DateTime(), default=sa.func.now(), onupdate=sa.func.now()),
+        sa.PrimaryKeyConstraint('id')
+    )
+    op.create_index(op.f('ix_todo_id'), 'todo', ['id'], unique=False)
+
+
+def downgrade() -> None:
+    op.drop_index(op.f('ix_todo_id'), table_name='todo')
+    op.drop_table('todo')

app/api/routes.py

@@ -0,0 +1,9 @@
+from fastapi import APIRouter
+
+from app.api import todos
+
+# API router
+router = APIRouter()
+
+# Include todo router
+router.include_router(todos.router, prefix="/todos", tags=["todos"])

app/api/todos.py

@@ -0,0 +1,101 @@
+from typing import Any, List, Optional
+
+from fastapi import APIRouter, Depends, HTTPException, Query, Path
+from sqlalchemy.orm import Session
+
+from app import models, schemas
+from app.db.deps import get_db
+
+router = APIRouter()
+
+
+@router.get("/", response_model=List[schemas.Todo])
+def read_todos(
+    skip: int = 0,
+    limit: int = 100,
+    completed: Optional[bool] = None,
+    db: Session = Depends(get_db),
+) -> Any:
+    """
+    Retrieve all todos with optional filtering by completed status
+    """
+    # Filter todos by completed status if provided
+    if completed is not None:
+        todos = db.query(models.Todo).filter(models.Todo.completed == completed).offset(skip).limit(limit).all()
+    else:
+        todos = db.query(models.Todo).offset(skip).limit(limit).all()
+    return todos
+
+
+@router.post("/", response_model=schemas.Todo, status_code=201)
+def create_todo(
+    todo_in: schemas.TodoCreate,
+    db: Session = Depends(get_db),
+) -> Any:
+    """
+    Create new todo
+    """
+    todo = models.Todo(
+        title=todo_in.title,
+        description=todo_in.description,
+        completed=todo_in.completed,
+    )
+    db.add(todo)
+    db.commit()
+    db.refresh(todo)
+    return todo
+
+
+@router.get("/{todo_id}", response_model=schemas.Todo)
+def read_todo(
+    todo_id: int = Path(..., gt=0),
+    db: Session = Depends(get_db),
+) -> Any:
+    """
+    Get a specific todo by id
+    """
+    todo = db.query(models.Todo).filter(models.Todo.id == todo_id).first()
+    if not todo:
+        raise HTTPException(status_code=404, detail="Todo not found")
+    return todo
+
+
+@router.put("/{todo_id}", response_model=schemas.Todo)
+def update_todo(
+    *,
+    todo_id: int = Path(..., gt=0),
+    todo_in: schemas.TodoUpdate,
+    db: Session = Depends(get_db),
+) -> Any:
+    """
+    Update a todo
+    """
+    todo = db.query(models.Todo).filter(models.Todo.id == todo_id).first()
+    if not todo:
+        raise HTTPException(status_code=404, detail="Todo not found")
+
+    update_data = todo_in.dict(exclude_unset=True)
+    for field, value in update_data.items():
+        setattr(todo, field, value)
+
+    db.add(todo)
+    db.commit()
+    db.refresh(todo)
+    return todo
+
+
+@router.delete("/{todo_id}", response_model=schemas.Todo)
+def delete_todo(
+    todo_id: int = Path(..., gt=0),
+    db: Session = Depends(get_db),
+) -> Any:
+    """
+    Delete a todo
+    """
+    todo = db.query(models.Todo).filter(models.Todo.id == todo_id).first()
+    if not todo:
+        raise HTTPException(status_code=404, detail="Todo not found")
+    
+    db.delete(todo)
+    db.commit()
+    return todo

app/core/config.py

@@ -0,0 +1,19 @@
+from pathlib import Path
+from typing import Any, Dict, Optional
+
+from pydantic import BaseSettings, validator
+
+
+class Settings(BaseSettings):
+    PROJECT_NAME: str = "Todo Backend Service"
+    API_V1_STR: str = "/api/v1"
+    
+    # Base directory
+    BASE_DIR: Path = Path(__file__).resolve().parent.parent.parent
+    
+    class Config:
+        env_file = ".env"
+        case_sensitive = True
+
+
+settings = Settings()

app/db/base.py

@@ -0,0 +1,3 @@
+# Import all models here for Alembic
+from app.models.todo import Todo
+from app.db.base_class import Base

app/db/base_class.py

@@ -0,0 +1,13 @@
+from typing import Any
+
+from sqlalchemy.ext.declarative import declared_attr
+from sqlalchemy.orm import DeclarativeBase
+
+
+class Base(DeclarativeBase):
+    id: Any
+    
+    # Generate __tablename__ automatically
+    @declared_attr
+    def __tablename__(cls) -> str:
+        return cls.__name__.lower()

app/db/deps.py

@@ -0,0 +1,16 @@
+from typing import Generator
+
+from sqlalchemy.orm import Session
+
+from app.db.session import SessionLocal
+
+
+def get_db() -> Generator[Session, None, None]:
+    """
+    Get database session dependency
+    """
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()

app/db/session.py

@@ -0,0 +1,17 @@
+from sqlalchemy import create_engine
+from sqlalchemy.orm import sessionmaker
+
+from app.core.config import settings
+
+# Create DB directory
+DB_DIR = settings.BASE_DIR / "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)

app/models/todo.py

@@ -0,0 +1,15 @@
+from datetime import datetime
+from typing import Optional
+
+from sqlalchemy import Boolean, Column, DateTime, Integer, String, Text
+
+from app.db.base_class import Base
+
+
+class Todo(Base):
+    id = Column(Integer, primary_key=True, index=True)
+    title = Column(String(100), nullable=False)
+    description = Column(Text, nullable=True)
+    completed = Column(Boolean, default=False)
+    created_at = Column(DateTime, default=datetime.utcnow)
+    updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)

app/schemas/todo.py

@@ -0,0 +1,38 @@
+from datetime import datetime
+from typing import Optional
+
+from pydantic import BaseModel, Field
+
+
+# Base Todo Schema for shared properties
+class TodoBase(BaseModel):
+    title: str = Field(..., min_length=1, max_length=100)
+    description: Optional[str] = None
+    completed: Optional[bool] = False
+
+
+# Schema for creating a todo
+class TodoCreate(TodoBase):
+    pass
+
+
+# Schema for updating a todo
+class TodoUpdate(BaseModel):
+    title: Optional[str] = Field(None, min_length=1, max_length=100)
+    description: Optional[str] = None
+    completed: Optional[bool] = None
+
+
+# Schema for returning a todo
+class TodoInDB(TodoBase):
+    id: int
+    created_at: datetime
+    updated_at: datetime
+
+    class Config:
+        orm_mode = True
+
+
+# Schema for public API
+class Todo(TodoInDB):
+    pass

main.py

@@ -0,0 +1,31 @@
+from fastapi import FastAPI
+from fastapi.middleware.cors import CORSMiddleware
+
+from app.api.routes import router as api_router
+from app.core.config import settings
+
+app = FastAPI(
+    title=settings.PROJECT_NAME,
+    description="Todo API backend service",
+    version="0.1.0",
+    openapi_url=f"{settings.API_V1_STR}/openapi.json",
+    docs_url="/docs",
+    redoc_url="/redoc",
+)
+
+# Set CORS middleware
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=["*"],
+    allow_credentials=True,
+    allow_methods=["*"],
+    allow_headers=["*"],
+)
+
+# Include API router
+app.include_router(api_router, prefix=settings.API_V1_STR)
+
+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>=0.103.1
+uvicorn>=0.23.2
+sqlalchemy>=2.0.21
+pydantic>=2.4.2
+alembic>=1.12.0
+python-dotenv>=1.0.0