python virtualenv和flask安装。 没有名为flask的模块

Question

I keep getting this error when running the basic program.

ImportError: No module named flask

Here's the basic prog:

from flask import Flask
app = Flask(__name__)

@app.route('/')
def hello_world():
    return 'Hello World!'

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

when I run which Flask on the folder it doesn't return the location. But if I run the pip install from there it says it's already installed.

Answer 1

If your want to create a project with Flask and VirtualENV, you should follow the steps below, I sure that you will not meet the error above.

Step 1: Create project directory and initial virtualenv directory

mkdir project 
cd project
virtualenv -p /usr/bin/python env

Step 2: Activate your virtual enviroment

source env/bin/activate

Step 3: Create requirements.txt file and add the content below:

Flask

Step 4: Install the packets with PIP

pip install -r requirements.txt

Step 5: Create your project file. Eg: run.py

from flask import Flask
app = Flask(__name__)

@app.route('/')
def hello_world():
    return 'Hello World!'

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

Step 6: Finally, run your app

python run.py

You will have some little works before publishing your code to repositories: init git, create gitignore ...

Answer 2

I hope you had installed virtualenv and if you have create the virtual environment (virtualenv), you have to use . . venv/bin/activate . venv/bin/activate command to activate the enviroment in unix or OSx. Hope you will get information from this source

http://flask.pocoo.org/docs/installation/#installation