I'm following the Flask Mega Tutorial, and I'm running into an issue once I get to the second part and restructure my folder structure to match theirs, I cannot import Flask.
My current folder structure is as follows
/FlaskTest
/app
/static, templates etc
/flask
/virtualenv folders etc
/tmp
run.py
as far as I can tell, the folder structures are identical other than naming of the top level directory.
in my __init__.py file (/app/__init__.py), I'm doing as instructed in the tutorial,
from flask import Flask
app = Flask(__name__)
from app import views
I'm getting an Import Error that "cannot import name 'Flask'". I'm guessing the issue is because the flask package was installed to /flask/lib/site-packages.
My question: How can I reference the sub folder of flask/site-packages?
I've read through the python import system documentation and from what I can make of it through the first pass of reading it over, I would need to likely do something like from flask import flask.Flask or something to that effect.
UPDATE: So after cd'ing around the directory and checking pip list, I realized that flask wasn't accessible to my app directory. I ran pip install flask in the app directory. Now my site runs, but I'm not sure if this is the best practice of doing things with Python. Please provide some clarity as what the best practice is for installing packages and where the packages reside.
UPDATE 2: After creating a directory called standalone. In this folder, I created a virtual environment called standalone-test. Once, I did that, I also mkdir'ed app and copied it's contents from FlaskTest so that way the code would be identical. I was able to run the run.py script by using python run.py, but I can't run python -m app like you had said without running into an error. The error is as follows if it helps.
"No module name app.main; 'app' is a package and cannot be directly executed.
I am able to run python run.py as I mentioned, but I'm not able to run the python -m app command as you had mentioned
I think something went wrong in your execution environment. Here are some explanations.
The virtualenv
See the documentation of virtualenv
If you have followed the tutorial:
The flask directory is your virtualenv,
On posix system, you have a flask/bin subdirectory, or
On Windows system, you have a flask\Scripts subdirectory.
I make the assumption that you are on posix system.
To activate your virtualenv, run:
source flask/bin/activate
Your prompt should change to something like: (flask)$.
To list the installed libraries use pip:
pip list
Make sure you see Flask. The tutorial encourages you to install a lot of Flask plugins, so there are a lot of Flask-Something…
If Flask is missing, install it:
pip install Flask
Run your app
Your application is in the app directory, it has an __init__.py file (it's a Python package).
In this file, you have:
from flask import Flask
app = Flask(__name__)
from app import views
From your FlaskTest/ directory, try to run this script like this:
cd FlaskTest/ # if not in this directory
python -m app
This should import Flask, instanciate your app (but don't run it), import the views module.
If app/views.py exist you should have no error.
=> at this point, we have simulated what run.py imports…
Now write run.py in your FlaskTest/ directory:
#!flask/bin/python
from app import app
app.run(debug=True)
Run it like this:
python run.py
Note that the shebang #!flask/bin/python is unusual, but should work in the context of the tutorial.
This should start your http server…
Related
In my main Python file, I import another script of mine called helper_1.py (from the subfolder my_helpers) like this:
from my_helpers.helper_1 as h1
However, when I now try to start my server (or deploy it to Heroku), the server will crash with the error notice:
ModuleNotFoundError: No module named 'my_helpers'
I do have a Procfile, requirements.txt, runtime.txt, and wsgi.py.
The content of my wsgi.py is:
from app.main import app
if __name__ == "__main__":
app.run()
MY QUESTION:
Where and how do I have to declare my custom modules (own scripts) so they are properly detected when starting the Flask server?
Everything works fine if I leave out the external reference to my custom module.
The folder my_helpers needs to be a package. To do this put an __init__.py file inside the my_helpers folder. This maybe fix your problem.
apologies if I'm going about this wrong, but I am quite new to python and can't quite figure out what the problem is! I have a simple Flask app that I'm trying to write tests using pytest for. The file structure is like this:
│── app.py
|── tests
│ ├── tests_app.py
I originally had app.py and tests_app.py in the same level and it all worked fine with tests passing, but now I have put tests in their own folder I can no longer import app without error.
I have tried the following in tests_app.py:
from app import app #this is what worked fine when app and tests were in the same folder
from ..app import app
from .. import app
and the linting error is 'Attempted relative import beyond top-level package' and when I run pytest it says 'ImportError: attempted relative import with no known parent package'.
Many thanks in advance!
p.s. I am using Python 3.8.5
You need to have app on the module search path. A quick fix would be to add the path to app.py to the PYTHONPATH environment variable:
export PYTHONPATH=/path/to/dir # where app.py is
If app.py is on the python path, then import app will work (barring any other import problems such as circular imports).
An effective and reproducible way to do this is to install your application. You can do this in develop mode, which means the code runs from its current directory. This is an understated, important part of developing a Python application, but to do it you will need to write code to package your application.
I have followed flask's tutorial to the point of installing the flaskr blog (here: http://flask.pocoo.org/docs/1.0/tutorial/install/). I'm new to installing python packages and I would appreciate some explanation of what's going on:
The tutorial says that installing the flaskr project has the benefit of being able to run it from anywhere.
However, I still can't run it outside the flask-tutorial directory (if I do flask run outside the flask-tutorial directory in the command line, I get flask.cli.NoAppException: Could not import "flaskr".)
Also, while I can import flaskr when working in the python interpreter, I also can't run it from there (even when I'm in the flask-tutorial directory):
import flaskr
app = flaskr.create_app()
app.run()
I get the following, and the python interpreter exits:
* Serving Flask app "flaskr" (lazy loading)
* Environment: development
* Debug mode: on
* Restarting with stat
/Users/user/projects/flask-tutorial/venv/scripts/python.exe can't find '__main__' module in ''
--- UPDATE:
If I set $env:FLASK_ENV = "production", and then start the python interpreter, I can run flaskr successfully as described above.
However, still no luck running flaskr directly from the command line (with flask run) outside of the flask-tutorial directory.
You are unable to use it outside the project folder because you have installed it in editable mode (-e flag). Uninstall the package and install again without the -e switch, so that it will be installed globally on your system. After that, it should work.
After successfully completing the pythonanywhere flask tutorial (pa.com), Miguel Grinberg's the "Flask Mega Tutorial" (fmt) beckoned. Sadly, I've not even made it to "Hello, World". Here's what I have done:
In pa.com attempting to follow fmt verbatim is a no go:
python3 -m venv flask
leads to an error of
ensurepip is not available
and we do not have sudo access.
Undeterred, I reasoned that all Miguel is asking us to do is distribute the functionality we see in one file in the pa.com tutorial (flask_app.py) into a few files that will make the building of a full app easier. Since pa.com is already setting up my base web app with flask and python 3.4, not being able to set up the virtual env. did not seem to be a block, at least not at first.
Per the fmt, in the base dir of the pa.com (pwd -> home/{username}/microblog) -- which is where the flask_app.py file that successfully generates the pa.com tutorial page lives -- I set up app and tmp directories, and create app/__init__.py, app/views.py and the run.py files as directed by fmt
Hitting the app page (run.py the only file in the main directory) generates an Unhandled Exception on the page.
Changing the name to flask_app.py (which seems to be what pa.com expects on flask installations) generates the same error.
Modifying the content of the flask_app.py code to:
from flask import Flask
app = Flask(__name__)
#app.route('/')
def hello_world():
return "working from flask_app.py"
Generates a successful output from the app, whereas having the same code in a file named run.py generates the same Unhandled Exception error.
the lines:
from app import app in both run.py and views.py and
from app import views in __init__.py
all make me wonder... where is this "app" module coming from? But aside from being puzzled by that question, no other ideas on how to proceed from here. Any suggestions? Would really like to get set up on pa.com and work through this tutorial/book.
Feel like I am missing something basic, but not sure what.
First rule is: don't use app.run() on PythonAnywhere - that's what run.py is trying to do. That's fine for your own PC, but on PA it will cause an error. It's fine to have the file there, but don't try and import from that file in your wsgi config.
Instead, you just need to import the flask app variable, which Miguel gets you to put in app/__init__.py (that's slightly confusing, a variable called app, and a folder called app, but we can deal with it!)
To do that, you'll want to add the folder that contains the app folder to your sys.path. You also need to "rename" the app variable to application as you import it:
# assuming we have /home/myusername/microblog/app/__init__.py:
path = '/home/myusername/microblog'
if path not in sys.path:
sys.path.append(path)
# now we can import the app variable from the app folder's __init__
# and rename it to application
from app import app as application
More info: a brief guide to flask on pythonanywhere and a guide to debugging imports and sys.path problems in your pythonanywhere wsgi file
from microblog import app as application
This is fixed my solution.
Best Regards
In my home directory, I have a folder called local. In it, there are files called __init__.py and local_settings.py. My django app is in a completely different directory. When the app is NOT running in DEBUG mode, I want it to load the local_settings.py file. How can this be acheived? I read the below:
Import a module from a relative path
Importing files from different folder in Python
http://docs.python.org/tutorial/modules.html
Basically, those tutorials are allowing to import from another directory, but what about a completely different working tree? I don't want to keep doing .., .., .. etc. Is there a way to goto the home directory?
I tried the following code:
import os, sys
os.chdir(os.path.join(os.getenv("HOME"), 'local'))
from local_settings import *
But i keep seeing errors in my apache error.log for it...
os.chdir just affects the current working directory, which has nothing whatsoever to do with where Python imports modules from.
What you need to do is to add the the local directory to the Pythonpath. You can either do this from the shell by modifying PYTHONPATH, or from inside Python by modifying sys.path:
import sys
import os
sys.path.append(os.path.expanduser("~/local"))
import local_settings
In response to your concerns about source control, you can just set the source control to ignore that file, and/or have a symlink installed as part of your deploy script to link the file on the os into another. I do both , though not in django. but it's a trivial task.
your deploy layout could look like this:
/current ( symlink to /releases/v3 )
/settings/local_settings.py
/releases/v1
/releases/v2
/releases/v3
and a task runs as part of your deploy:
cd /current
ln -s /settings/local_settings.py local_settings.py
if you're deploying with fab or capistrano, it's a few lines of configuration. i'm sure you could do this with puppet/chef simply too.