envclasses 0.2.0

A library to map dataclass and environmental variables

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

envclass is a meta programming library on top of dataclass. Once envclass decorator is specified in a dataclass, It will generate dunder function which loads values from environment variables. This functionality is very useful in a case like you want to override the exisiting configurations for an application by the ones defined in environment variables.

Requirements

python >= 3.6.0

Installation

• Install from PyPI

  pip install envclasses
  

• Install development version from Github

  pip install git+https://github.com/yukinarit/WebSocketSample.git
  

Usage

• Create Hoge instance

  from typing import List, Dict
  from dataclasses import dataclass, field
  from envclasses import envclass, load_env
  
  
  @envclass
  @dataclass
  class Hoge:
      i: int
      s: str
      f: float
      b: bool
      lst: List[int] = field(default_factory=list)
      dct: Dict[str, float] = field(default_factory=dict)
  
  
  # Create an instance.
  hoge = Hoge(i=10, s='hoge', f=0.1, b=False)
  
  # Load values from environment variables.
  load_env(hoge, prefix='HOGE')
  
  print(hoge)
  

• Run

  $ python hoge.py
  

  Hoge(i=10, s='hoge', f=0.1, b=False, lst=[], dct={})
  

• Override Hoge values by environment variables

  $ export HOGE_I=20
  $ export HOGE_S=hogehoge
  $ export HOGE_F=0.2
  $ export HOGE_B=true
  $ export HOGE_DCT="{'key': 100.0}"
  $ export HOGE_LST="[1, 2, 3]"
  $ python hoge.py
  

  Hoge(i=20, s='hogehoge', f=0.2, b=True, lst=[1, 2, 3], dct={'key': 100.0})