Create a REST API with FastAPI and SQLite

- Setup FastAPI project structure with main.py and requirements.txt
- Implement SQLAlchemy ORM with SQLite database
- Create Item model with CRUD operations
- Implement health endpoint for monitoring
- Setup Alembic for database migrations
- Add comprehensive documentation in README.md
- Configure Ruff for code linting

README.md

@@ -1,3 +1,127 @@
-# FastAPI Application
+# REST API Service
 
-This is a FastAPI application bootstrapped by BackendIM, the AI-powered backend generation platform.
+A modern REST API service built with FastAPI and SQLite.
+
+## Features
+
+- **FastAPI Framework**: High-performance, easy to learn, fast to code, ready for production
+- **SQLAlchemy ORM**: SQL toolkit and Object-Relational Mapping
+- **SQLite Database**: Lightweight disk-based database
+- **Alembic Migrations**: Database migration tool for SQLAlchemy
+- **Pydantic Models**: Data validation and settings management
+- **OpenAPI Documentation**: Interactive API documentation at /docs and /redoc
+- **Health Check Endpoint**: Monitoring endpoint for service health
+
+## Project Structure
+
+```
+.
+├── alembic.ini                  # Alembic configuration
+├── app                          # Application package
+│   ├── api                      # API endpoints
+│   │   ├── __init__.py         # API router setup
+│   │   ├── health.py           # Health check endpoint
+│   │   └── items.py            # Items endpoints
+│   ├── core                     # Core application configuration
+│   │   └── config.py           # Application settings
+│   ├── crud                     # CRUD operations
+│   │   ├── __init__.py         # CRUD exports
+│   │   ├── base.py             # Base CRUD class
+│   │   └── crud_item.py        # Item CRUD operations
+│   ├── db                       # Database setup
+│   │   └── session.py          # Database session management
+│   ├── models                   # SQLAlchemy models
+│   │   ├── __init__.py         # Model exports
+│   │   └── item.py             # Item model
+│   └── schemas                  # Pydantic schemas
+│       ├── __init__.py         # Schema exports
+│       └── item.py             # Item schemas
+├── main.py                      # Application entry point
+├── migrations                   # Database migrations
+│   ├── env.py                  # Alembic environment configuration
+│   ├── script.py.mako          # Alembic template for migrations
+│   └── versions                # Migration scripts
+│       └── initial_migration.py # Initial database schema
+└── requirements.txt            # Python dependencies
+```
+
+## Installation
+
+1. Clone the repository:
+   ```bash
+   git clone <repository-url>
+   cd <repository-name>
+   ```
+
+2. Create a virtual environment:
+   ```bash
+   python -m venv venv
+   source venv/bin/activate  # On Windows: venv\Scripts\activate
+   ```
+
+3. Install dependencies:
+   ```bash
+   pip install -r requirements.txt
+   ```
+
+4. Run database migrations:
+   ```bash
+   alembic upgrade head
+   ```
+
+## Running the Application
+
+Start the application with Uvicorn:
+
+```bash
+uvicorn main:app --reload
+```
+
+The API will be available at http://localhost:8000
+
+## API Documentation
+
+- **OpenAPI Swagger UI**: http://localhost:8000/docs
+- **ReDoc**: http://localhost:8000/redoc
+
+## API Endpoints
+
+### Health Check
+
+- `GET /api/v1/health`: Check the health of the API
+
+### Items
+
+- `GET /api/v1/items/`: Get all items
+- `POST /api/v1/items/`: Create a new item
+- `GET /api/v1/items/{item_id}`: Get an item by ID
+- `PUT /api/v1/items/{item_id}`: Update an item
+- `DELETE /api/v1/items/{item_id}`: Delete an item
+
+## Database
+
+The application uses SQLite as its database, stored at `/app/storage/db/db.sqlite`.
+
+## Development
+
+### Creating a new migration
+
+After making changes to the SQLAlchemy models, create a new migration script:
+
+```bash
+alembic revision --autogenerate -m "Description of changes"
+```
+
+### Running migrations
+
+Apply all pending migrations:
+
+```bash
+alembic upgrade head
+```
+
+Revert the last migration:
+
+```bash
+alembic downgrade -1
+```

alembic.ini

@@ -0,0 +1,103 @@
+# 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
+
+# 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 migrations/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:migrations/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
+
+# SQLite URL - using absolute path
+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

app/api/__init__.py

@@ -0,0 +1,7 @@
+from fastapi import APIRouter
+
+from app.api import health, items
+
+api_router = APIRouter()
+api_router.include_router(health.router, tags=["health"])
+api_router.include_router(items.router, tags=["items"])

app/api/health.py

@@ -0,0 +1,30 @@
+from datetime import datetime
+
+from fastapi import APIRouter, Depends
+from sqlalchemy.orm import Session
+
+from app.db.session import get_db
+
+router = APIRouter()
+
+
+@router.get("/health", summary="Health check endpoint")
+def health_check(db: Session = Depends(get_db)):
+    """
+    Check the health of the API.
+    
+    Returns:
+        dict: Health status information including uptime and database status
+    """
+    db_status = "ok"
+    try:
+        # Test database connection
+        db.execute("SELECT 1")
+    except Exception as e:
+        db_status = f"error: {str(e)}"
+
+    return {
+        "status": "ok",
+        "timestamp": datetime.utcnow().isoformat(),
+        "database": db_status,
+    }

app/api/items.py

@@ -0,0 +1,135 @@
+from typing import Any, List
+
+from fastapi import APIRouter, Depends, HTTPException, status
+from sqlalchemy.orm import Session
+
+from app import crud, schemas
+from app.db.session import get_db
+
+router = APIRouter()
+
+
+@router.get("/items/", response_model=List[schemas.Item])
+def read_items(
+    db: Session = Depends(get_db),
+    skip: int = 0,
+    limit: int = 100,
+    active_only: bool = False,
+) -> Any:
+    """
+    Retrieve items.
+    
+    Args:
+        skip: Number of items to skip
+        limit: Maximum number of items to return
+        active_only: If True, only return active items
+    
+    Returns:
+        List of items
+    """
+    if active_only:
+        items = crud.item.get_multi_active(db, skip=skip, limit=limit)
+    else:
+        items = crud.item.get_multi(db, skip=skip, limit=limit)
+    return items
+
+
+@router.post("/items/", response_model=schemas.Item, status_code=status.HTTP_201_CREATED)
+def create_item(
+    *,
+    db: Session = Depends(get_db),
+    item_in: schemas.ItemCreate,
+) -> Any:
+    """
+    Create new item.
+    
+    Args:
+        item_in: Item data
+    
+    Returns:
+        Created item
+    """
+    item = crud.item.get_by_title(db, title=item_in.title)
+    if item:
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail="An item with this title already exists.",
+        )
+    item = crud.item.create(db, obj_in=item_in)
+    return item
+
+
+@router.get("/items/{item_id}", response_model=schemas.Item)
+def read_item(
+    *,
+    db: Session = Depends(get_db),
+    item_id: int,
+) -> Any:
+    """
+    Get item by ID.
+    
+    Args:
+        item_id: ID of item to get
+    
+    Returns:
+        Item information
+    """
+    item = crud.item.get(db=db, id=item_id)
+    if not item:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail="Item not found",
+        )
+    return item
+
+
+@router.put("/items/{item_id}", response_model=schemas.Item)
+def update_item(
+    *,
+    db: Session = Depends(get_db),
+    item_id: int,
+    item_in: schemas.ItemUpdate,
+) -> Any:
+    """
+    Update an item.
+    
+    Args:
+        item_id: ID of item to update
+        item_in: New item data
+    
+    Returns:
+        Updated item
+    """
+    item = crud.item.get(db=db, id=item_id)
+    if not item:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail="Item not found",
+        )
+    item = crud.item.update(db=db, db_obj=item, obj_in=item_in)
+    return item
+
+
+@router.delete("/items/{item_id}", response_model=schemas.Item)
+def delete_item(
+    *,
+    db: Session = Depends(get_db),
+    item_id: int,
+) -> Any:
+    """
+    Delete an item.
+    
+    Args:
+        item_id: ID of item to delete
+    
+    Returns:
+        Deleted item
+    """
+    item = crud.item.get(db=db, id=item_id)
+    if not item:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail="Item not found",
+        )
+    item = crud.item.remove(db=db, id=item_id)
+    return item

app/core/config.py

@@ -0,0 +1,28 @@
+from pathlib import Path
+
+from pydantic_settings import BaseSettings
+
+
+class Settings(BaseSettings):
+    # API configuration
+    API_V1_STR: str = "/api/v1"
+    PROJECT_NAME: str = "RESTAPIService"
+    PROJECT_DESCRIPTION: str = "FastAPI REST API Service"
+    VERSION: str = "0.1.0"
+
+    # CORS Origins
+    BACKEND_CORS_ORIGINS: list[str] = ["*"]
+
+    # Database
+    DB_DIR = Path("/app") / "storage" / "db"
+    DB_DIR.mkdir(parents=True, exist_ok=True)
+
+    # SQLite Database URL
+    SQLALCHEMY_DATABASE_URL: str = f"sqlite:///{DB_DIR}/db.sqlite"
+
+    class Config:
+        case_sensitive = True
+        env_file = ".env"
+
+
+settings = Settings()

app/crud/__init__.py

@@ -0,0 +1,3 @@
+from app.crud.crud_item import item  # noqa: F401
+
+__all__ = ["item"]

app/crud/base.py

@@ -0,0 +1,66 @@
+from typing import Any, Dict, Generic, List, Optional, Type, TypeVar, Union
+
+from fastapi.encoders import jsonable_encoder
+from pydantic import BaseModel
+from sqlalchemy.orm import Session
+
+from app.db.session import Base
+
+ModelType = TypeVar("ModelType", bound=Base)
+CreateSchemaType = TypeVar("CreateSchemaType", bound=BaseModel)
+UpdateSchemaType = TypeVar("UpdateSchemaType", bound=BaseModel)
+
+
+class CRUDBase(Generic[ModelType, CreateSchemaType, UpdateSchemaType]):
+    def __init__(self, model: Type[ModelType]):
+        """
+        CRUD object with default methods to Create, Read, Update, Delete (CRUD).
+        
+        **Parameters**
+        
+        * `model`: A SQLAlchemy model class
+        * `schema`: A Pydantic model (schema) class
+        """
+        self.model = model
+
+    def get(self, db: Session, id: Any) -> Optional[ModelType]:
+        return db.query(self.model).filter(self.model.id == id).first()
+
+    def get_multi(
+        self, db: Session, *, skip: int = 0, limit: int = 100
+    ) -> List[ModelType]:
+        return db.query(self.model).offset(skip).limit(limit).all()
+
+    def create(self, db: Session, *, obj_in: CreateSchemaType) -> ModelType:
+        obj_in_data = jsonable_encoder(obj_in)
+        db_obj = self.model(**obj_in_data)  # type: ignore
+        db.add(db_obj)
+        db.commit()
+        db.refresh(db_obj)
+        return db_obj
+
+    def update(
+        self,
+        db: Session,
+        *,
+        db_obj: ModelType,
+        obj_in: Union[UpdateSchemaType, Dict[str, Any]]
+    ) -> ModelType:
+        obj_data = jsonable_encoder(db_obj)
+        if isinstance(obj_in, dict):
+            update_data = obj_in
+        else:
+            update_data = obj_in.model_dump(exclude_unset=True)
+        for field in obj_data:
+            if field in update_data:
+                setattr(db_obj, field, update_data[field])
+        db.add(db_obj)
+        db.commit()
+        db.refresh(db_obj)
+        return db_obj
+
+    def remove(self, db: Session, *, id: int) -> ModelType:
+        obj = db.query(self.model).get(id)
+        db.delete(obj)
+        db.commit()
+        return obj

app/crud/crud_item.py

@@ -0,0 +1,26 @@
+from typing import List, Optional
+
+from sqlalchemy.orm import Session
+
+from app.crud.base import CRUDBase
+from app.models.item import Item
+from app.schemas.item import ItemCreate, ItemUpdate
+
+
+class CRUDItem(CRUDBase[Item, ItemCreate, ItemUpdate]):
+    def get_by_title(self, db: Session, *, title: str) -> Optional[Item]:
+        return db.query(Item).filter(Item.title == title).first()
+
+    def get_multi_active(
+        self, db: Session, *, skip: int = 0, limit: int = 100
+    ) -> List[Item]:
+        return (
+            db.query(Item)
+            .filter(Item.is_active == True)  # noqa: E712
+            .offset(skip)
+            .limit(limit)
+            .all()
+        )
+
+
+item = CRUDItem(Item)

app/db/session.py

@@ -0,0 +1,27 @@
+from pathlib import Path
+
+from sqlalchemy import create_engine
+from sqlalchemy.ext.declarative import declarative_base
+from sqlalchemy.orm import sessionmaker
+
+from app.core.config import settings
+
+# Ensure DB directory exists
+Path(settings.DB_DIR).mkdir(parents=True, exist_ok=True)
+
+engine = create_engine(
+    settings.SQLALCHEMY_DATABASE_URL,
+    connect_args={"check_same_thread": False}  # needed only for SQLite
+)
+SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
+
+Base = declarative_base()
+
+
+# Dependency to get DB session
+def get_db():
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()

app/models/__init__.py

@@ -0,0 +1,3 @@
+from app.models.item import Item  # noqa: F401
+
+__all__ = ["Item"]

app/models/item.py

@@ -0,0 +1,15 @@
+from sqlalchemy import Boolean, Column, DateTime, Integer, String
+from sqlalchemy.sql import func
+
+from app.db.session import Base
+
+
+class Item(Base):
+    __tablename__ = "items"
+
+    id = Column(Integer, primary_key=True, index=True)
+    title = Column(String, index=True)
+    description = Column(String, index=True)
+    is_active = Column(Boolean(), default=True)
+    created_at = Column(DateTime(timezone=True), server_default=func.now())
+    updated_at = Column(DateTime(timezone=True), onupdate=func.now())

app/schemas/__init__.py

@@ -0,0 +1,3 @@
+from app.schemas.item import Item, ItemCreate, ItemInDB, ItemUpdate  # noqa: F401
+
+__all__ = ["Item", "ItemCreate", "ItemUpdate", "ItemInDB"]

app/schemas/item.py

@@ -0,0 +1,45 @@
+from datetime import datetime
+from typing import Optional
+
+from pydantic import BaseModel, Field
+
+
+# Shared properties
+class ItemBase(BaseModel):
+    title: Optional[str] = None
+    description: Optional[str] = None
+    is_active: Optional[bool] = True
+
+
+# Properties to receive on item creation
+class ItemCreate(ItemBase):
+    title: str = Field(..., min_length=1, max_length=100)
+    description: str = Field(..., min_length=1)
+
+
+# Properties to receive on item update
+class ItemUpdate(ItemBase):
+    pass
+
+
+# Properties shared by models stored in DB
+class ItemInDBBase(ItemBase):
+    id: int
+    title: str
+    description: str
+    is_active: bool
+    created_at: datetime
+    updated_at: Optional[datetime] = None
+
+    class Config:
+        from_attributes = True
+
+
+# Properties to return to client
+class Item(ItemInDBBase):
+    pass
+
+
+# Properties stored in DB
+class ItemInDB(ItemInDBBase):
+    pass

main.py

@@ -0,0 +1,20 @@
+
+import uvicorn
+from fastapi import FastAPI
+
+from app.api import api_router
+from app.core.config import settings
+
+app = FastAPI(
+    title=settings.PROJECT_NAME,
+    description=settings.PROJECT_DESCRIPTION,
+    version=settings.VERSION,
+    openapi_url=f"{settings.API_V1_STR}/openapi.json",
+    docs_url="/docs",
+    redoc_url="/redoc",
+)
+
+app.include_router(api_router, prefix=settings.API_V1_STR)
+
+if __name__ == "__main__":
+    uvicorn.run("main:app", host="0.0.0.0", port=8000, reload=True)

migrations/env.py

@@ -0,0 +1,80 @@
+from logging.config import fileConfig
+
+from alembic import context
+from sqlalchemy import engine_from_config, pool
+
+# 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.session import Base
+from app.models import Item  # noqa
+
+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:
+        is_sqlite = connection.dialect.name == "sqlite"
+        context.configure(
+            connection=connection,
+            target_metadata=target_metadata,
+            render_as_batch=is_sqlite,  # Enable batch mode for SQLite
+        )
+
+        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() -> None:
+    ${upgrades if upgrades else "pass"}
+
+
+def downgrade() -> None:
+    ${downgrades if downgrades else "pass"}

migrations/versions/initial_migration.py

@@ -0,0 +1,39 @@
+"""initial migration
+
+Revision ID: 000001
+Revises: 
+Create Date: 2023-07-01
+
+"""
+import sqlalchemy as sa
+from alembic import op
+
+# revision identifiers, used by Alembic.
+revision = '000001'
+down_revision = None
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    # Create items table
+    op.create_table(
+        'items',
+        sa.Column('id', sa.Integer(), nullable=False),
+        sa.Column('title', sa.String(), nullable=True),
+        sa.Column('description', sa.String(), nullable=True),
+        sa.Column('is_active', sa.Boolean(), nullable=True, default=True),
+        sa.Column('created_at', sa.DateTime(timezone=True), server_default=sa.text('(CURRENT_TIMESTAMP)')),
+        sa.Column('updated_at', sa.DateTime(timezone=True), nullable=True),
+        sa.PrimaryKeyConstraint('id')
+    )
+    op.create_index(op.f('ix_items_id'), 'items', ['id'], unique=False)
+    op.create_index(op.f('ix_items_title'), 'items', ['title'], unique=False)
+    op.create_index(op.f('ix_items_description'), 'items', ['description'], unique=False)
+
+
+def downgrade() -> None:
+    op.drop_index(op.f('ix_items_description'), table_name='items')
+    op.drop_index(op.f('ix_items_title'), table_name='items')
+    op.drop_index(op.f('ix_items_id'), table_name='items')
+    op.drop_table('items')

pyproject.toml

@@ -0,0 +1,25 @@
+[tool.ruff]
+line-length = 100
+target-version = "py310"
+
+[tool.ruff.lint]
+# Enable Pyflakes, pycodestyle, isort
+select = ["F", "E", "W", "I"]
+
+# Ignore specific rules
+ignore = [
+    "E501",  # Line too long
+    "W293",  # Blank line contains whitespace - docstrings often have this
+]
+
+# Exclude files and directories
+exclude = [
+    ".git",
+    ".venv",
+    "venv",
+    "__pycache__",
+    "migrations",
+]
+
+[tool.ruff.lint.isort]
+known-third-party = ["fastapi", "pydantic", "sqlalchemy", "alembic", "starlette"]

requirements.txt

@@ -0,0 +1,9 @@
+fastapi>=0.100.0
+uvicorn>=0.23.0
+sqlalchemy>=2.0.0
+pydantic>=2.0.0
+alembic>=1.11.0
+python-dotenv>=1.0.0
+ruff>=0.0.272
+email-validator>=2.0.0
+pydantic[email]>=2.0.0