Classy Env

About

Classy Env is a lightweight Python package for managing environment variables in an OOP way.

Requirements

This package requires Python 3.11 or higher.

Installation

Classy Env is available on PyPI and can be installed by running the following command:

pip install classy-env

Usage

Create a ClassyEnv subclass and declare its attributes using the EnvVar function:

from classyenv import ClassyEnv, EnvVar

class Settings(ClassyEnv):
    database_user = EnvVar("DB_USER")
    database_password = EnvVar("DB_PASSWORD")
    api_secret_key = EnvVar("SECRET_KEY")

The EnvVar function takes the name of the environment variable as an argument. The Value of that variable will be assigned to the corresponding attribute.

Then, create an object of your subclass and access the environment variables through the object's attributes:

settings = Settings()

database_connection = connect(
    user=settings.database_user,
    password=settings.database_password,
)

At the object's creation, Classy Env will check if the environment variables provided to the EnvVar functions are defined. If not, an exception will be raised.

Runtime validation

added in version 1.1.0

The validation mentioned above can also be triggered at class creation using the runtime_check class argument:

from classyenv import ClassyEnv, EnvVar

class Settings(ClassyEnv, runtime_check=True):
    database_user = EnvVar("DB_USER")
    database_password = EnvVar("DB_PASSWORD")
    api_secret_key = EnvVar("SECRET_KEY")

Converters

added in version 1.2.0

The EnvVar function accepts an optional converter argument. Converter must be a callable that accepts a string value.

If provided, converter will be called with the environment variable value when the attribute is being accessed, and the returned by converter value will be returned as attribute value:

from classyenv import ClassyEnv, EnvVar

class Settings(ClassyEnv):
    database_port: int = EnvVar("DB_PORT", converter=int)


settings = Settings()
assert isinstance(settings.database_port, int)

Defaults

added in version 1.3.0

The EnvVar function accepts an optional default argument, which allows for specifying a default value, when corresponding environment variable is not defined:

import os
from classyenv import ClassyEnv, EnvVar

if "DB_PORT" in os.environ:
    os.environ.pop("DB_PORT")

class Settings(ClassyEnv):
    database_port = EnvVar("DB_PORT", default=3306)


settings = Settings()
assert settings.database_port == 3306

Mutating the ClassyEnv instances and subclasses

At this moment, mutating instances of the ClassyEnv class is not supported:

settings.database_user = "Roe_Jogan123" # this will raise an exception

Similarly, mutating the class attributes of the ClassyEnv subclasses is not supported:

Settings.database_user = "Roe_Jogan123" # this will raise an exception

License

This project is licensed under the terms of the MIT license.