typing.NamedTuple with pydantic.

area_pydantic.py

from contextlib import suppress
from typing import NamedTuple

from pydantic import create_model_from_namedtuple, BaseModel, root_validator


class FunctionNumber101(NamedTuple):
    width: float
    height: float

    def area(cls, values=None):
        try:
            values = cls._asdict()
        except AttributeError:
            values = {x: y for x, y in zip(cls.__fields__, values.values())}
        if values['width'] <= 0 or values['height'] <= 0:
            raise ValueError("width and height must be positive")
        if not hasattr(cls, '__fields__'):
            return values['width'] * values['height']
        return values


def namedtuple_to_basemodel(nt, *args):
    nt_methods = {}
    nt_input = {x: y for x, y in zip(nt._fields, args)}
    tuple_methods = 'count', 'index'
    for method_name in dir(nt):
        method = getattr(nt, method_name)
        callable_ = callable(method)
        not_tuple_method = method_name not in tuple_methods
        if method_name.isalpha() and callable_ and not_tuple_method:
            nt_methods[method_name] = root_validator(method)
    pydantic_model = create_model_from_namedtuple(nt, __validators__=nt_methods)
    return pydantic_model(**nt_input)


def get_rectangle_area(width: float, height: float):
    model = namedtuple_to_basemodel(FunctionNumber101, width, height)
    assert isinstance(model, BaseModel)


get_rectangle_area(10, 1)

square = FunctionNumber101(10, 10)
assert square.area() == 100