Hello,
In this segment, we are talking about the configuration file. We’re going to talk about the configuration method, using a config file.
The configuration is an important part of any application and, Flask provides many different ways to configure your application like setting your environment type and depending upon there database.
Config basics
Every Flask application has a global config object which can be accessed via app.config.
config object allows us to assign values to configuration variables, which can be used in the application.
You can see your Global config objects just simply print it one of your routes. Go ahead and add the following line.
print(app.config)
And you will see this in your terminal.
{
'ENV': 'development',
'DEBUG': False,
'TESTING': False,
'PROPAGATE_EXCEPTIONS': None,
'PRESERVE_CONTEXT_ON_EXCEPTION': None,
'SECRET_KEY': None,
'PERMANENT_SESSION_LIFETIME': datetime.timedelta(31),
'USE_X_SENDFILE': False,
'SERVER_NAME': None,
'APPLICATION_ROOT': '/',
'SESSION_COOKIE_NAME': 'session',
'SESSION_COOKIE_DOMAIN': None,
'SESSION_COOKIE_PATH': None,
'SESSION_COOKIE_HTTPONLY': True,
'SESSION_COOKIE_SECURE': False,
'SESSION_COOKIE_SAMESITE': None,
'SESSION_REFRESH_EACH_REQUEST': True,
'MAX_CONTENT_LENGTH': None,
'SEND_FILE_MAX_AGE_DEFAULT': datetime.timedelta(0, 43200),
'TRAP_BAD_REQUEST_ERRORS': None,
'TRAP_HTTP_EXCEPTIONS': False,
'EXPLAIN_TEMPLATE_LOADING': False,
'PREFERRED_URL_SCHEME': 'http',
'JSON_AS_ASCII': True,
'JSON_SORT_KEYS': True,
'JSONIFY_PRETTYPRINT_REGULAR': False,
'JSONIFY_MIMETYPE': 'application/json',
'TEMPLATES_AUTO_RELOAD': None,
'MAX_COOKIE_SIZE': 4093,
}
All these are the default built-in configurationvariables, which we can modify and change.
To change any of these variable, we just need to assign a new value to the key:
app.config["KEY"] = "value
For example, let’s update the configuration SECRET_KEY variable with the following:
app.config["SECRET_KEY"] = "qwert653443"
print(app.config["SECRET_KEY"])
You’ll see the following in your terminal:
qwert653443
Let us define a config file for our application.
App config file
Flask allows us to create a custom config file.
so it can overwrite the default config variables.
So let’s create of config.py file in the root folder.
<root>/config.py
class Config(object):
DEBUG = False
TESTING = False
class Production(Config):
pass
class Development(Config):
DEBUG = True
We first create the Config class and set some default attributes.
We have created 3 more classes and each of which inherits the Config class and attributes.
- Production - Is the config class we’ll use for running in production
- Development - Is the config class we’ll use for development
Let’s create our config file
class Config:
"""Base config."""
SECRET_KEY = "worldisbest"
STATIC_FOLDER = 'static'
TEMPLATES_FOLDER = 'templates'
DEBUG = True
class Production(Config):
FLASK_ENV = 'production'
DEBUG = False
TESTING = False
class Development(Config):
FLASK_ENV = 'development'
DEBUG = True
TESTING = True
We’ve assigned new values
Now that we’ve created our config file, we’ll need to instruct Flask to load it.
Loading a config file
Adding a config file is a simple one-liner and should be placed as close to wherever you’ve created your app object.
The best way to add a config file is just after you create your app object.
We load a config file with from_object() method
e.g. app.config.from_object"config_filename.ConfigClass")
If you want to load the Development class, we would do the following.
app.config.from_object("config.Development")
If you want to load the Production class, we would do the following.
app.config.from_object("config.Production")
And after all, you open your __init__.py file
add your config statement just bellow your app = Flask(__name__) line
app = Flask(__name__)
app.config.from_object("config.Development")
We can also use the ENV variable to set the condition in which the config file will load.
ENV environment
The ENV environment configuration variable is important and should always be set outside of your application, which we set with FLASK_ENV from the terminal.
Like in the first segment of the series
By default , ENV set to production which disables the DEBUG mode and avoids displaying the interactive debugger
Setting FLASK_ENV=development enables the debugger, which should never, ever be done in production!
Now when we set the ENV variable so we can so with the following:
app = Flask(__name__)
if app.config["ENV"] == "production":
app.config.from_object("config.Production")
else:
app.config.from_object("config.Development")
This allows us to control the config environment outside the application by setting the FLASK_ENV environment variable in the terminal.
IF you set FLASK_ENV to development
$ export FLASK_ENV=development
$ flask run
* Environment: development
* Debug mode: on
* Running on http://127.0.0.1:5000/ (Press CTRL+C to quit)
* Restarting with stat
* Debugger is active!
* Debugger PIN: 249-444-542
Now repeat the process, changing FLASK_ENV to production:
$ export FLASK_ENV=production
$ flask run
* Environment: production
WARNING: This is a development server. Do not use it in a production deployment.
Use a production WSGI server instead.
* Debug mode: off
Wrapping up
In this segment we have learn about seting up the config file.
Try to do some project by yourself.
In the upcoming segment we are learing about linking Database to our application.