Flaskr

Flaskr is a minimal blog application built with the Python web framework Flask that supports one user's posting entries. This is the code produced by following the tutorial at: http://flask.pocoo.org/docs/0.12/tutorial/.

Requirements

• Python 2.7 or Python 3.4+

Installation

Install the app from the root directory (where setup.py lives).

$ pip install --editable .

Run Flaskr

Set our environment variables, so Flask knows what application to run and whether to give you debug information. Note: Do not set FLASK_DEBUG to true with a publicly exposed application, because it makes your system vulnerable.

On Mac and Linux set the environment variables with:

$ export FLASK_APP=flaskr
$ export FLASK_DEBUG=true

On Windows set the environment variables with:

$ set FLASK_APP=flaskr
$ set FLASK_DEBUG=true

Initialize the database (only do this once unless you want to delete any blog posts you create).

$ flask initdb

Start our web server to run Flaskr.

$ flask run

Windows Troubleshooting

• If you get an error about pip not being found when running the command $ pip install --editable ., this is because pip.exe is not on your PATH environment variable. Navigate to where you can modify your environment variables at: Control Panel → System and Security → System → Advanced system settings → Environment variables

Then under the user variables select the PATH variable for editing and add these two paths, separating them with semicolons if needed and changing the paths below to the correct username and Python version.

C:\Users\username\AppData\Local\Programs\Python\Python36-32\Scripts\
C:\Users\username\AppData\Local\Programs\Python\Python36-32\

The \Scripts directory is where pip.exe and flask.exe are installed.

• If you get a UTF-8 related error when attempting flask run, try turning off the Flask debug, which may be causing the problem.

$ set FLASK_DEBUG=false

Exercise

For a next step, create another page on your blog site that serves up a single blog entry based on the blog entry's id:

• The page should be accessed at the path /entry/<id>. For example, a page to serve up your first entry, that would have id 1, would be at http://127.0.0.1:5000/entry/1.
• You can create a new template, perhaps called entry.html, that inherits from the layout.html template. Bonus: modify the show_entries.html template to provide a link to individual entries from each entry shown in the list of entries.

Other tutorials

• https://blog.miguelgrinberg.com/post/the-flask-mega-tutorial-part-i-hello-world - More robust Flask tutorial that considers production relevant issues such as virtual environments, SQLAlchemy extension to provide an Object Relational Mapper that abstracts working with the database, database migrations, multiple users, handling logins, creating user profile pages with avatars via gravatar, etc.
• https://www.tutorialspoint.com/flask/flask_overview.htm - Separate brief lessons covering various Flask topics.