Error message "python-pylint 'C0103:Invalid constant name"

Xing picture Xing · Dec 18, 2016 · Viewed 44.8k times · Source

I'm confused about the error(s) in this photo:

Enter image description here

I don't know how to fix them. My program is a Python-Flask web frame. When I use Visual Studio Code to debug my program, Pylint shows these errors. I know this problem doesn't matter, but it makes me annoyed. How can I fix it?

# -*- coding: utf-8 -*-
import sys
from flask import Flask
from flask_bootstrap import Bootstrap
from flask_moment import Moment
#from flask_wtf import Form
#from wtforms import StringField, SubmitField
#from wtforms.validators import Required
from flask_sqlalchemy import SQLAlchemy

reload(sys)
sys.setdefaultencoding('utf-8')

app = Flask(__name__)
app.config['SECRET_KEY'] = 'hard to guess string'
app.config['SQLALCHEMY_DATABASE_URI'] = 'mysql://root:@localhost:3306/test?'
app.config['SQLALCHEMY_COMMIT_ON_TEARDOWN'] = True
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = True

bootstrap = Bootstrap(app)
moment = Moment(app)
db = SQLAlchemy(app)


if __name__ == '__main__':
    db.create_all()
    app.run()

Answer

sthenault picture sthenault · Dec 19, 2016

As explained by Kundor, PEP 8 states that:

Constants are usually defined on a module level and written in all capital letters with underscores separating words.

The point is that "constants" in Python don't really exist. Pylint, as per PEP 8, expects module level variables to be "constants."

That being said you've several options:

  • you don't want this "constant" thing, then change Pylint's const-rgx regular expression to be the same as e.g. variable-rgx,

  • you may deactivate those warnings for this file, or even locally in the file, using # pylint: disable=invalid-name,

  • avoid module level variables, by wrapping them into a function.

In your case, I would go with the third option, by creating a build_app function or something similar. That would return the application (and maybe the 'db' object as well, but you have several choices there). Then you could add a salt of the second option to get something like:

app = build_app() # pylint: disable=invalid-name