decouple-example/README.md at master · ISP21/decouple-example

Simple Example of Externalizing Data

Externalize the name of the file containing student data.

Requires: python-decouple (pip3 install python-decouple)

First: run gitstudents.py. It works, but the filename is hardcoded. Not very maintainable.

Let's improve it:

create a file named .env containing this:

# name of file containing student data
CSVFILE = "students.csv"

In gitstudents.py, add:
```
from decouple import config
```
And read the filename from the configuration file (.env):
```
datafile = config('CSVFILE')
data = open(datafile)
```
Run the code. It should still work.
- You can rename the file (and change .env) and it still works -- no need to modify code.
Externalize the number of students to print (10). In .env add:
```
count = 10
```
In the Python code:
```
count = config('count', default=10, cast=int)  
```
cast=int means to convert the value to int; the default is to return the value as a string.
Run it. It should still work. But now you want to print 20 students.
In .env change the value of count to 20. Run the code again. Does it work?