Bendykit

Code generator for Python backends following DDD principles.

Describe your domain in a single Python file, get a full stack: domain models, repository, use cases, DTOs and FastAPI routers. Architecture is Onion, no ActiveRecord, strict layer separation.

Installation

pip install bendykit

Usage

# manifest.py
from decimal import Decimal
from enum import Enum
from typing import Optional
from datetime import datetime

from bendy import Aggregate, ValueObject, Field, auto_now


class OrderStatus(Enum):
    PENDING = "pending"
    CONFIRMED = "confirmed"


class Address(ValueObject):
    street: str
    city: str
    country: str = "US"


class Order(Aggregate):
    customer_id: str
    total_amount: Decimal
    status: OrderStatus = OrderStatus.PENDING
    shipping_address: Address
    notes: Optional[str] = None
    created_at: datetime = auto_now

    class Meta:
        use_cases = ["create", "get", "update", "delete", "list"]

bendykit manifest.py ./src

Generates for each aggregate:

src/order/
├── domain/
│   ├── models.py        # @dataclass Order
│   ├── enums.py         # OrderStatus(Enum)
│   ├── value_objects.py # @dataclass(frozen=True) Address
│   └── repository.py    # OrderRepository(ABC)
├── application/
│   ├── dtos.py          # OrderCreate / OrderUpdate / OrderResponse
│   └── use_cases.py     # Create/Get/Update/Delete/ListOrderUseCase
├── presentation/
│   └── router.py        # FastAPI router
└── infrastructure/
    ├── models.py        # OrderModel(Base) — SQLAlchemy 2.0
    └── repository.py    # SqlalchemyOrderRepository + mapper

Types

Manifest	Python	SQLAlchemy
str	str	String
int	int	Integer
float	float	Float
bool	bool	Boolean
Decimal	Decimal	Numeric
datetime	datetime	DateTime
date	date	Date
UUID	UUID	String
Optional[X]	Optional[X]	nullable=True
MyEnum(Enum)	MyEnum	String + mapper
MyVO(ValueObject)	MyVO	JSON

Manifest primitives

• auto_now — value is set server-side, excluded from Create/Update DTOs
• Field(unique=True, index=True, max_length=N) — column metadata
• ValueObject — nested object without id, stored as JSON
• Meta.use_cases — operations to generate: create, get, update, delete, list (default: create, get)

Roadmap

• Phase I — CLI generator
• Phase II — Python manifests (Enum, ValueObject, Field, auto_now, Meta)
• Phase III — bendykit.runtime: Unit of Work, Domain Events

License

MIT