Reading bash environment variable set using parameter substitution into Python variable

Question

I have the following environment variables in my .env file:

DT="2019-01-01"
X=${DT//-/}

The variable X has been set using Bash's parameter replacement, using the ${parameter//pattern/string} format to replace all occurrences (Documentation here).

Now, to read the environment variables into Python, I have created a Python class Config in a file config.py:

from dotenv import find_dotenv, load_dotenv
import os

class Config:
    def __init__(self):
        load_dotenv(find_dotenv())

        self.X = os.environ.get('X')

In a python shell, I run:

In [1]: from config import Config

In [2]: c = Config()

In [3]: c.X
Out[3]: ''

Here c.X is an empty string '', where as I want it to be '20190101'.

How do I load the correct value of the environment variable into a python variable?

Edit: When I type echo $X in a bash script, it prints the correct value. For example, a bash script sample.sh:

#!/bin/bash
source .env

echo $X

When run, I get:

$ sh sample.sh
20190101

Answer 1

I added an export in my .env file in this way:

DT="2019-01-01"
export X=${DT//-/}

This allowed me to get the correct value of c.X in Python.