| |
  ___ _ ____   _____| | __ _ ___ ___  ___  ___
 / _ \ '_ \ \ / / __| |/ _` / __/ __|/ _ \/ __|
|  __/ | | \ V / (__| | (_| \__ \__ \  __/\__ \
 \___|_| |_|\_/ \___|_|\__,_|___/___/\___||___/

envclass is a small library which maps environment variables dataclass's fields This is very useful in a case like you want to override the configurations read from file.

Installation

pip install envclasses

Usage

# foo.py
from typing import List, Dict
from dataclasses import dataclass, field
from envclasses import envclass, load_env

@envclass
@dataclass
class Foo:
    i: int
    s: str
    f: float
    b: bool
    lst: List[int] = field(default_factory=list)
    dct: Dict[str, float] = field(default_factory=dict)

foo = Foo(i=10, s='foo', f=0.1, b=False)

# Map environment variables to fields.
load_env(foo, prefix='FOO')

print(foo)

run

$ python foo.py
Foo(i=10, s='foo', f=0.1, b=False, lst=[], dct={})

Run with environment variables

$ FOO_I=20 FOO_S=foofoo FOO_F=0.2FOO_B=true FOO_DCT="{key: 100.0}" FOO_LST="[1, 2, 3]" python foo.py
Foo(i=20, s='foofoo', f=0.2, b=True, lst=[1, 2, 3], dct={'key': 100.0})

Notes:

• If prefix is not defined or set to None, the default prefix (ENV_) will be expected.
• If prefix is set to the empty string '', no prefix will be expected in the environment variables.