Betwixt¶

Betwixt your data models lives a new, declarative mapping layer.

Overview¶

If you've ever worked with advanced data types such as Pydantic models or SQLAlchemy ORM models, you know that translating data between them can be a tricky operation. Two models can describe the same thing while using different field names, nesting, or representations. Betwixt lets you describe those differences once, then move data between the models in either direction.

Basic Example¶

from dataclasses import dataclass
from betwixt import Betwixt, field_refs, map_rightward

@dataclass
class Left:
    value: int

@dataclass
class Right:
    value: int

left_refs, right_refs = field_refs(Left, Right)

class Mapping(Betwixt):
    left = Left
    right = Right
    value = map_rightward(left=left_refs.value, right=right_refs.value, rightward=lambda value: value)

assert Mapping().rightward(Left(3)) == Right(3)

What next¶

• Start with the quickstart, then follow the User, Payment, and Order cases.
• Learn the basic Concepts to better understand what Betwixt is all about.
• Read the Comparison to see how Betwixt cleanly replaces fragmented translation machinery.