Can I format dataclass attributes in python?

Question

I am trying to creating a python dataclass where fields can have formatted values. If I have the following

@dataclass(kw_only=True)
class childtestProduct(testProduct):

  t1:float 
  t2:str

how can I have for example t1 be like 99.90€ and t2 be like 10/8/2002 ?

Asked By: N Miaoulis

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Source

Answer 1

You could use an approach with @property decorator, as mentioned, and turn all dataclass fields into field properties:

from dataclasses import dataclass
from datetime import datetime, date


@dataclass(kw_only=True)
class ChildTestProduct:
    t1: float
    t2: datetime | str

    @property
    def t1(self) -> str:
        return f'{self._t1:.2f}€'

    @t1.setter
    def t1(self, value: float):
        self._t1 = value

    @property
    def t2(self) -> str:
        return self._t2.strftime('%m/%d/%Y')

    @t2.setter
    def t2(self, value: datetime | str):
        if isinstance(value, str):
            self._t2 = datetime.strptime(value, '%m/%d/%y').date()
        else:
            self._t2 = value


p = ChildTestProduct(t1=99.9, t2='10/8/22')
print(p)  # ChildTestProduct(t1='99.90€', t2='10/08/2022')

assert isinstance(p._t1, float)
assert isinstance(p._t2, date)

Answered By: rv.kvetch

Can I format dataclass attributes in python?

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