Materials for the Flask ILLO @ DIB Lab, October 15, 2018.
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Charles Reid e3b3c215b4 update readme and add tests 1 year ago
.. update readme and add tests 1 year ago
requirements.txt add our simplest flask example 1 year ago update readme and add tests 1 year ago update readme and add tests 1 year ago

hello: flask hello world

Flask home page:

the simplest flask app

Here is the simplest Flask app:

from flask import Flask
app = Flask(__name__)

def hello():
    return "Hello World!"

This directory contains files to get this server up and running.

hello: quick start

how to set up this directory

Create a virtual environment, which we’ll call vp (you can use any name you want):

virtualenv vp

This creates a “clean” version of python and pip that are separate from your
normal version of Python and pip.

To install Flask into this virtual environment:

pip install -r requirements.txt

The requirements.txt file just contains the name of any Python packages
that should be installed, and optional version numbers. In this case, we
only install Flask, so the contents of requirements.txt is:


how to run the web app

The Flask web application is stored in the variable app (see

To run the Flask app, you call

how to test the web app

To test the simple Flask web app, you can use the Python unittest module from
the command line:

python -m unittest discover

This will find and run the Flask test.

To run a Flask test, you only need to create the test client - the server is taken
care of for you.

client = app.test_client()

This is a built-in Flask method that returns a client object.

The client object can run get and post methods on URLs.
The simple server only needs get methods to test routes:

# Test route /
r = client.get('/')
assert b'Hello world!' in