Flask Snippets

overview // docs // community // snippets // extensions // search

Preconfigured interactive shell

By Dag Odenhall filed in Utilities

The documentation recommends putting imports in a module and import that when you're in an interactive session. Even better, I think, is to make an executable that launches a preconfigured Python shell.

Put something like this in for example shell.py and run chmod +x shell.py.

#!/usr/bin/env python

import os
import readline
from pprint import pprint

from flask import *

from myapp import *
from utils import *
from db import *
from models import *


os.environ['PYTHONINSPECT'] = 'True'

Normally import * should be avoided but unless you get namespace collisions it makes sense for an interactive shell environment.

Now you can simply do ./shell.py.

This snippet by Dag Odenhall can be used freely for anything you like. Consider it public domain.

Comments

Using werkzeug.script by Dan Jacob on 2010-05-28 @ 07:16

Another way to create a ready shell is to use the werkzeug.script library detailed here:

http://werkzeug.pocoo.org/documentation/0.6.1/script.html

For my Flask project I have also have a shell.py script:

"""
Creates shell using IPython
"""
import sys

from werkzeug import script

from myapp import create_app, models
from myapp.database import metadata, db_session

def make_shell():
    try:
        config = sys.argv[1]
    except IndexError:
        config = "dev.cfg"

    return dict(app=create_app(config),
                models=models,
                db_session=db_session,
                metadata=metadata,)

if __name__ == "__main__":

    script.make_shell(make_shell, use_ipython=True)()

This will use IPython automatically if installed.

The make_shell function passes a dict of variables you want included automatically in your shell - in this case the app instance, models module and SQLAlchemy session and metadata (as most of the time I will need to access the database).

werkzeug.script by Dan Jacob on 2010-05-28 @ 08:02
Armin may be planning a rewrite of werkzeug.script, but until we know what that's going to look like it's still part of the Werkzeug package.

I would therefore use it and change the code as and when needed.
Re: Using werkzeug.script by Dag Odenhall on 2010-05-28 @ 07:58
I used werkzeug.script first but:
```
<donri> "Further Improving the Shell Experience" why not use
        werkzeugs manage scripts?
<DasIch> donri: mitsuhiko is planning on rewriting 
         werkzeug.script
```
Also import * raises a SyntaxWarning if not used at the top-level, and I couldn't even suppress the exception.

If however werkzeug.script works for you, there are of course benefits to it such as easily setting up a runserver command, or any other custom commands.
Flask-Script by Dag Odenhall on 2010-07-21 @ 00:54
Flask-Script is now an option that's looking good; although it might have the same issue with import *.

Simulating import * with Flask-Script by Dag Odenhall on 2010-08-09 @ 16:47

I solved the issue with SyntaxWarning. The warnings module didn't help but I realised this rather obvious solution:

@manager.shell
def shell_context():

    import pprint

    import flask

    import vlasisku

    context = dict(pprint=pprint.pprint)
    context.update(vars(flask))
    context.update(vars(myapp))
    context.update(vars(myapp.utils))
    context.update(vars(myapp.database))
    context.update(vars(myapp.models))

    return context