Flask Run - ImportError was raised-CodePudding

Starting my Flask app using:

flask run

Doesn't appear to work... and I get the error message:

Error: While importing 'entry', an ImportError was raised.

however if I run:

python entry.py

The app will build successfully? Why is this? Both FLASK_APP and FLASK_ENV are set correctly, here is my folder structure:

entry.py:

from application import create_app

app = create_app()
if __name__ == '__main__':
    app.run(host='0.0.0.0', port=8080)

application/init.py:

import os
from flask import Flask
from config import DevConfig, TestConfig, ProdConfig
from flask_sqlalchemy import SQLAlchemy

db = SQLAlchemy()

from application.models import Report


def create_app(testing=False):
    app = Flask(__name__)

    flask_env = os.getenv("FLASK_ENV", None)

    # Configure the application, depending on the environment
    if testing:
        app.config.from_object(TestConfig)
    elif flask_env == "development":
        app.config.from_object(DevConfig)
    elif flask_env == "production":
        app.config.from_object(ProdConfig)
    else:
        raise ValueError("FLASK_ENV is not set or there is an unknown environment type!")

    # init plugins, if any
    db.init_app(app)

    if flask_env == "development":
        with app.app_context():
            db.create_all()
            db.session.commit()

    # register blueprints
    register_blueprints(app)

    return app


def register_blueprints(app):
    from application.main import main_blueprint

    app.register_blueprint(main_blueprint)

CodePudding user response：

If you want to start the application through the flask executable, then you have to consider that flask will look for the app.py file containing the app application, if not (as in your case), then you will have to correctly set the value of the environment variable FLASK_APP, which will be equal to FLASK_APP=entry.py:app

On Linux, macOS:

$ export FLASK_APP=entry.py:app
$ flask run

On Windows:

$ set FLASK_APP=entry.py:app
$ flask run

Take a look here: Run The Application.

Here, however, it is explained how flask looks for the application to run

In this case (python entry.py) everything works correctly, because flask is invoked via python inside the main section, which instead is not called if entry.py is executed directly from flask, in fact flask will not enter the main section, but will look for the app.py file and the app variable inside it. (Obviously it will look for entry.py and app if you have configured the environment variable correctly)