Implement REST API with FastAPI and SQLite

- Set up project structure and dependencies
- Implement database models with SQLAlchemy
- Set up Alembic migrations
- Create FastAPI application with CORS support
- Implement API endpoints (CRUD operations)
- Add health check endpoint
- Update README with setup and usage instructions
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# FastAPI Application
# Generic REST API
This is a FastAPI application bootstrapped by BackendIM, the AI-powered backend generation platform.
A generic REST API built with FastAPI and SQLite, providing CRUD operations for managing items.
## Features
- FastAPI framework with automatic documentation (OpenAPI)
- SQLAlchemy ORM for database interactions
- Alembic for database migrations
- SQLite database (no external database required)
- CORS support (enabled for all origins)
- Health check endpoint
- RESTful API design
- Pydantic models for validation
## Requirements
- Python 3.8+
- pip for package installation
## Project Structure
```
.
├── alembic.ini # Alembic configuration
├── app # Application package
│ ├── api # API endpoints
│ │ ├── deps.py # API dependencies
│ │ └── v1 # API version 1
│ │ ├── api.py # API router
│ │ └── endpoints # API endpoint modules
│ │ ├── health.py # Health check endpoint
│ │ └── items.py # Items CRUD endpoints
│ ├── core # Core modules
│ │ └── config.py # Application configuration
│ ├── crud # CRUD operations
│ │ ├── base.py # Base CRUD operations
│ │ └── item.py # Item-specific CRUD
│ ├── db # Database
│ │ ├── base.py # Base model imports
│ │ ├── base_class.py # Base model class
│ │ └── session.py # Database session
│ ├── models # SQLAlchemy models
│ │ └── item.py # Item model
│ └── schemas # Pydantic schemas
│ └── item.py # Item schemas
├── main.py # Application entry point
├── migrations # Alembic migrations
│ ├── env.py # Alembic environment
│ ├── script.py.mako # Migration script template
│ └── versions # Migration versions
│ └── 001_create_item_table.py # Initial migration
└── requirements.txt # Package requirements
```
## Installation
1. Clone the repository:
```bash
git clone <repository-url>
cd genericrestapi
```
2. Install the dependencies:
```bash
pip install -r requirements.txt
```
3. Run the database migrations:
```bash
alembic upgrade head
```
## Running the API
Start the FastAPI application:
```bash
uvicorn main:app --host 0.0.0.0 --port 8000 --reload
```
The API will be available at `http://localhost:8000`.
## API Documentation
Once the application is running, you can access the API documentation:
- Swagger UI: `http://localhost:8000/docs`
- ReDoc: `http://localhost:8000/redoc`
- OpenAPI JSON: `http://localhost:8000/openapi.json`
## API Endpoints
### Items
- `GET /api/v1/items`: List all items
- `POST /api/v1/items`: Create a new item
- `GET /api/v1/items/{id}`: Get item details
- `PUT /api/v1/items/{id}`: Update an item
- `DELETE /api/v1/items/{id}`: Delete an item
### Health
- `GET /api/v1/health`: Check API health status
## Environment Variables
This application does not require any environment variables to run, as it uses SQLite as the database which is automatically configured.
## Development
- The SQLite database is stored at `/app/storage/db/db.sqlite`
- Database migrations can be created using Alembic: `alembic revision -m "description"`
- Use Ruff for linting: `ruff check .`

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# A generic, single database configuration.
[alembic]
# path to migration scripts
script_location = migrations
# 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
# see https://alembic.sqlalchemy.org/en/latest/tutorial.html#editing-the-ini-file
# for all available tokens
# 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 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 example - using absolute path for database
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

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# API module initialization

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from typing import Generator
from app.db.session import SessionLocal
def get_db() -> Generator:
"""
Dependency for database session.
"""
db = SessionLocal()
try:
yield db
finally:
db.close()

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# API v1 module initialization

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from fastapi import APIRouter
from app.api.v1.endpoints import items, health
api_router = APIRouter()
api_router.include_router(health.router, prefix="/health", tags=["health"])
api_router.include_router(items.router, prefix="/items", tags=["items"])

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# API endpoints module initialization

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from typing import Dict
from fastapi import APIRouter, Depends, status
from sqlalchemy.orm import Session
from sqlalchemy import text
from app.api.deps import get_db
from app.core.config import settings
router = APIRouter()
@router.get("/", status_code=status.HTTP_200_OK)
def health_check(db: Session = Depends(get_db)) -> Dict[str, str]:
"""
Check the health of the application.
Returns:
Dict with status and version information.
"""
# Check database connection
try:
db.execute(text("SELECT 1"))
db_status = "healthy"
except Exception:
db_status = "unhealthy"
return {
"status": "ok" if db_status == "healthy" else "error",
"version": settings.PROJECT_VERSION,
"database": db_status
}

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from typing import Any, List
from fastapi import APIRouter, Depends, HTTPException, status
from sqlalchemy.orm import Session
from app import crud
from app.api.deps import get_db
from app.schemas.item import Item, ItemCreate, ItemUpdate
router = APIRouter()
@router.get("/", response_model=List[Item])
def read_items(
db: Session = Depends(get_db),
skip: int = 0,
limit: int = 100,
active_only: bool = False,
) -> Any:
"""
Retrieve items with pagination.
- **skip**: Number of items to skip
- **limit**: Maximum number of items to return
- **active_only**: If true, only return active items
"""
if active_only:
items = crud.item.get_active(db, skip=skip, limit=limit)
else:
items = crud.item.get_multi(db, skip=skip, limit=limit)
return items
@router.post("/", response_model=Item, status_code=status.HTTP_201_CREATED)
def create_item(
*,
db: Session = Depends(get_db),
item_in: ItemCreate,
) -> Any:
"""
Create a new item.
"""
item = crud.item.create(db, obj_in=item_in)
return item
@router.get("/{id}", response_model=Item)
def read_item(
*,
db: Session = Depends(get_db),
id: int,
) -> Any:
"""
Get a specific item by ID.
"""
item = crud.item.get(db, id=id)
if not item:
raise HTTPException(
status_code=status.HTTP_404_NOT_FOUND,
detail="Item not found",
)
return item
@router.put("/{id}", response_model=Item)
def update_item(
*,
db: Session = Depends(get_db),
id: int,
item_in: ItemUpdate,
) -> Any:
"""
Update an item.
"""
item = crud.item.get(db, id=id)
if not item:
raise HTTPException(
status_code=status.HTTP_404_NOT_FOUND,
detail="Item not found",
)
item = crud.item.update(db, db_obj=item, obj_in=item_in)
return item
@router.delete("/{id}", status_code=status.HTTP_204_NO_CONTENT, response_model=None)
def delete_item(
*,
db: Session = Depends(get_db),
id: int,
) -> None:
"""
Delete an item.
"""
item = crud.item.get(db, id=id)
if not item:
raise HTTPException(
status_code=status.HTTP_404_NOT_FOUND,
detail="Item not found",
)
crud.item.remove(db, id=id)
return None

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# Core module initialization

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from pathlib import Path
from pydantic_settings import BaseSettings
class Settings(BaseSettings):
# Project settings
PROJECT_NAME: str = "Generic REST API"
PROJECT_DESCRIPTION: str = "A generic REST API built with FastAPI and SQLite"
PROJECT_VERSION: str = "0.1.0"
# Database settings
DB_DIR: Path = Path("/app") / "storage" / "db"
SQLALCHEMY_DATABASE_URL: str = f"sqlite:///{DB_DIR}/db.sqlite"
class Config:
env_file = ".env"
case_sensitive = True
# Create settings instance
settings = Settings()
# Ensure DB directory exists
settings.DB_DIR.mkdir(parents=True, exist_ok=True)

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from app.crud.item import item
# Export all CRUD instances
__all__ = ["item"]

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from typing import Any, Dict, Generic, List, Optional, Type, TypeVar, Union
from pydantic import BaseModel
from sqlalchemy.orm import Session
from fastapi.encoders import jsonable_encoder
from app.db.base_class 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]:
"""Get a single record by ID."""
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]:
"""Get multiple records with pagination."""
return db.query(self.model).offset(skip).limit(limit).all()
def create(self, db: Session, *, obj_in: CreateSchemaType) -> ModelType:
"""Create a new record."""
obj_in_data = jsonable_encoder(obj_in)
db_obj = self.model(**obj_in_data)
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:
"""Update a record."""
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:
"""Delete a record."""
obj = db.query(self.model).get(id)
db.delete(obj)
db.commit()
return obj

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from typing import List, Optional
from sqlalchemy.orm import Session
from app.models.item import Item
from app.schemas.item import ItemCreate, ItemUpdate
from app.crud.base import CRUDBase
class CRUDItem(CRUDBase[Item, ItemCreate, ItemUpdate]):
def get_by_name(self, db: Session, *, name: str) -> Optional[Item]:
"""Get an item by name."""
return db.query(Item).filter(Item.name == name).first()
def get_active(self, db: Session, *, skip: int = 0, limit: int = 100) -> List[Item]:
"""Get active items with pagination."""
return db.query(Item).filter(Item.is_active).offset(skip).limit(limit).all()
# Create an instance for importing in other modules
item = CRUDItem(Item)

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# Import all models here for Alembic to detect

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

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from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker
from pathlib import Path
# Ensure the database directory exists
DB_DIR = Path("/app") / "storage" / "db"
DB_DIR.mkdir(parents=True, exist_ok=True)
# SQLite database URL
SQLALCHEMY_DATABASE_URL = f"sqlite:///{DB_DIR}/db.sqlite"
# Create engine with check_same_thread=False for SQLite
engine = create_engine(
SQLALCHEMY_DATABASE_URL,
connect_args={"check_same_thread": False}
)
# Create SessionLocal class
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
def get_db():
"""Database dependency for FastAPI endpoints."""
db = SessionLocal()
try:
yield db
finally:
db.close()

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from sqlalchemy import Column, Integer, String, Text, DateTime, Boolean
from sqlalchemy.sql import func
from app.db.base_class import Base
class Item(Base):
"""Database model for items."""
id = Column(Integer, primary_key=True, index=True)
name = Column(String(255), nullable=False, index=True)
description = Column(Text, nullable=True)
price = Column(Integer, nullable=False) # Price in cents
is_active = Column(Boolean, default=True)
created_at = Column(DateTime(timezone=True), server_default=func.now())
updated_at = Column(DateTime(timezone=True), server_default=func.now(), onupdate=func.now())

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from typing import Optional
from datetime import datetime
from pydantic import BaseModel, Field, ConfigDict
# Base schema for item shared properties
class ItemBase(BaseModel):
name: str = Field(..., min_length=1, max_length=255)
description: Optional[str] = None
price: int = Field(..., ge=0) # Price in cents, must be >= 0
is_active: bool = True
# Schema for creating an item
class ItemCreate(ItemBase):
pass
# Schema for updating an item
class ItemUpdate(BaseModel):
name: Optional[str] = Field(None, min_length=1, max_length=255)
description: Optional[str] = None
price: Optional[int] = Field(None, ge=0)
is_active: Optional[bool] = None
# Schema for item response
class Item(ItemBase):
id: int
created_at: datetime
updated_at: datetime
model_config = ConfigDict(from_attributes=True)

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import uvicorn
from fastapi import FastAPI
from fastapi.middleware.cors import CORSMiddleware
from pathlib import Path
from app.api.v1.api import api_router
from app.core.config import settings
app = FastAPI(
title=settings.PROJECT_NAME,
description=settings.PROJECT_DESCRIPTION,
version=settings.PROJECT_VERSION,
openapi_url="/openapi.json",
docs_url="/docs",
redoc_url="/redoc",
)
# Set up CORS middleware
app.add_middleware(
CORSMiddleware,
allow_origins=["*"],
allow_credentials=True,
allow_methods=["*"],
allow_headers=["*"],
)
# Include API router
app.include_router(api_router, prefix="/api/v1")
# Create database directory if it doesn't exist
DB_DIR = Path("/app") / "storage" / "db"
DB_DIR.mkdir(parents=True, exist_ok=True)
if __name__ == "__main__":
uvicorn.run("main:app", host="0.0.0.0", port=8000, reload=True)

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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 # 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"},
# Enable batch mode for SQLite
render_as_batch=True,
)
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:
# Check if we're using SQLite
is_sqlite = connection.dialect.name == 'sqlite'
context.configure(
connection=connection,
target_metadata=target_metadata,
# Enable batch mode for SQLite
render_as_batch=is_sqlite,
)
with context.begin_transaction():
context.run_migrations()
if context.is_offline_mode():
run_migrations_offline()
else:
run_migrations_online()

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"""${message}
Revision ID: ${up_revision}
Revises: ${down_revision | comma,n}
Create Date: ${create_date}
"""
from typing import Sequence, Union
from alembic import op
import sqlalchemy as sa
${imports if imports else ""}
# revision identifiers, used by Alembic.
revision: str = ${repr(up_revision)}
down_revision: Union[str, None] = ${repr(down_revision)}
branch_labels: Union[str, Sequence[str], None] = ${repr(branch_labels)}
depends_on: Union[str, Sequence[str], None] = ${repr(depends_on)}
def upgrade() -> None:
${upgrades if upgrades else "pass"}
def downgrade() -> None:
${downgrades if downgrades else "pass"}

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"""Create item table
Revision ID: 001
Revises:
Create Date: 2023-11-15
"""
from typing import Sequence, Union
from alembic import op
import sqlalchemy as sa
# revision identifiers, used by Alembic.
revision: str = '001'
down_revision: Union[str, None] = None
branch_labels: Union[str, Sequence[str], None] = None
depends_on: Union[str, Sequence[str], None] = None
def upgrade() -> None:
# Create item table
op.create_table(
'item',
sa.Column('id', sa.Integer(), nullable=False),
sa.Column('name', sa.String(255), nullable=False, index=True),
sa.Column('description', sa.Text(), nullable=True),
sa.Column('price', sa.Integer(), nullable=False),
sa.Column('is_active', sa.Boolean(), default=True),
sa.Column('created_at', sa.DateTime(timezone=True), server_default=sa.func.now()),
sa.Column('updated_at', sa.DateTime(timezone=True), server_default=sa.func.now(), onupdate=sa.func.now()),
sa.PrimaryKeyConstraint('id')
)
# Create index on name for faster lookups
op.create_index(op.f('ix_item_name'), 'item', ['name'], unique=False)
# Create index on id column
op.create_index(op.f('ix_item_id'), 'item', ['id'], unique=False)
def downgrade() -> None:
# Drop indexes
op.drop_index(op.f('ix_item_name'), table_name='item')
op.drop_index(op.f('ix_item_id'), table_name='item')
# Drop item table
op.drop_table('item')

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fastapi==0.104.1
uvicorn==0.23.2
sqlalchemy==2.0.23
alembic==1.12.1
pydantic==2.4.2
pydantic[email]==2.4.2
python-dotenv==1.0.0
ruff==0.1.5