Flask ImportError: No Module Named Flask

Question

I'm following the Flask tutorial here:

http://blog.miguelgrinberg.com/post/the-flask-mega-tutorial-part-i-hello-world

I get to the point where I try ./run.py and I get:

Traceback (most recent call last):
  File "./run.py", line 3, in <module>
    from app import app
  File "/Users/benjaminclayman/Desktop/microblog/app/__init__.py", line 1, in <module>
    from flask import Flask
ImportError: No module named flask

This looks similar to:

ImportError: No module named flask

But their solutions aren't helpful. For reference, I do have a folder named flask which one user mentioned may cause issues.

Answer 1

Try deleting the virtualenv you created. Then create a new virtualenv with:

virtualenv flask

Then:

cd flask

Now let's activate the virtualenv

source bin/activate

Now you should see (flask) on the left of the command line.

_{Edit: In windows there is no "source" that's a linux thing, instead execute the activate.bat file, here I do it using Powershell: PS C:\DEV\aProject> & .\Flask\Scripts\activate)}

Let's install flask:

pip install flask

Then create a file named hello.py (NOTE: see UPDATE Flask 1.0.2 below):

from flask import Flask
app = Flask(__name__)

@app.route("/")
def hello():
    return "Hello World!"

if __name__ == "__main__":
    app.run()

and run it with:

python hello.py

UPDATE Flask 1.0.2

With the new flask release there is no need to run the app from your script. hello.py should look like this now:

from flask import Flask
app = Flask(__name__)

@app.route("/")
def hello():
    return "Hello World!"

and run it with:

FLASK_APP=hello.py flask run

Make sure to be inside the folder where hello.py is when running the latest command.

All the steps before the creation of the hello.py apply for this case as well