cast-from-env

Get and cast environment variables

Installation

python setup.py install

Usage

Call from_env() with the name of an environment variable, and either a default value to return if the environment variable is not set, or a type to cast the environment variable's value to if it is set. If a default value is passed and the variable is set, its value will be cast to the type of the default value.

Actually, any callable can be passed as the second parameter, and will be used to cast the value if it's not None. So if you pass e.g. json.loads a JSON env var value will be cast to a Python list or dict.

Also, if the type of the default value – or the type passed in instead – is bool, from_env() will return True if the environment variable's string value is any of '1', 'true', 't', 'yes', 'y', and 'on', and False otherwise.

Examples

from cast_from_env import from_env
from json import loads

from_env('STRING_VAR', 'default value')  # Value or 'default value' if not set
from_env('INTEGER_VAR', 100)  # Value cast to int, or 100 if not set
from_env('INTEGER_VAR', int)  # Value cast to int, or None if not set
from_env('FLOAT_VAR', 1.0)  # Value cast to float, or 1.0 if not set
from_env('TRUE_VAR', bool)  # True if value is '1', 'true', 'yes', or 'on'
from_env('TRUE_VAR', True)  # True if value is '1', 'true', 'yes', 'on', or not set
from_env('TEST_JSON', loads)  # JSON string is cast to Python list or dict