Storing database location and credential variables Python/Flask app

Question

I'm going through an online tutorial for building a Python/Flask app. Before I installed Postgres and messed with my database I could launch my app from command line no problem. Now, everytime I restart the command prompt I have to redefine the APP_SETTINGS and DATABASE_URL variables. The app works fine after I refine the variables, but I know this isn't the way its supposed to work. The errors are below:

 Traceback (most recent call last):
 File "app.py", line 12, in <module>
 app.config.from_object(os.environ['APP_SETTINGS'])
 File "C:\envs\acme\lib\os.py", line 423, in __getitem__
 return self.data[key.upper()]
 KeyError: 'APP_SETTINGS'

I'll then redefine the variable using "set":

set APP_SETTINGS=config.DevelopmentConfig

Here is the code I use for my app.py and config.py

config.py:

import os
# default config
class BaseConfig(object):
    DEBUG = False
    SECRET_KEY = 'secret key'
    SQLALCHEMY_DATABASE_URI = os.environ['DATABASE_URL']

class DevelopmentConfig(BaseConfig):
    DEBUG = True

class ProductionConfig(BaseConfig):
    DEBUG = False

app.py

import os
app.config.from_object(os.environ['APP_SETTINGS'])

The same thing goes for the DATABASE_URL variable listed above in the config.py file. I also get a KEYERROR and must redefine the variable using "set" as well as type in my username and password below:

set DATABASE_URL=postgres://username:password@localhost/discover_flask_dev

I'm using Windows 8 and Python 2.7. I have these tools installed in my environment:

Flask==0.10.1
Flask-SQLAlchemy==2.0
Jinja2==2.7.3
MarkupSafe==0.23
SQLAlchemy==0.9.8
Werkzeug==0.9.6
gunicorn==19.1.1
ipython==2.3.0
itsdangerous==0.24
psycopg2==2.5.2
pyreadline==2.0

I'm assuming there is a basic method to solve my problem mentioned above. Please advice. Thanks!

Community · Accepted Answer · 2017-03-20 10:18:27Z

1

Your key issue, it seems, is "everytime I restart the command prompt I have to redefine the APP_SETTINGS and DATABASE_URL variables".

From this superuser answer, it looks like there are two environment variable commands: SET (which reverts on command window close), and SETX (which persists after command window close).

Instead of
set DATABASE_URL=postgres://username:password@localhost/discover_flask_dev

Try using
setx DATABASE_URL "postgres://username:password@localhost/discover_flask_dev"

Note the slightly different syntax: SETX uses double quotes "..", and does not use equals =

edited Mar 20, 2017 at 10:18

CommunityBot

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answered Oct 28, 2014 at 2:54

rosshamish

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2 Comments

user3474515 Over a year ago

I did what you said and also started using Git Bash and the problem went away. Thanks!

rosshamish Over a year ago

Great! If you'd like to indicate that this answer solved the problem, please click the green checkmark to accept it.

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