Flask Quick Primer

Overview

This repo is a quick primer on using the Flask micro-framework.

The primer is done via a code progression using tags. The tags can be viewed by either execvuting git tag in the repository or on the GitHub Tags page. Each tag represents added functionality in the primer.

Obtaining the Primer

To obtain the primer, simply clone the repository.

Git CLI Example:

git clone https://github.com/aenglander/lvpython-flask-talk.git
cd lvpython-flask-talk

Viewing the Primer Sections

Primer sections are designated with Git tags.

Git CLI Example:

$ git tag
1-hello-world
2-variable-routes
3-jinja-templates
4-reverse-routing-for-links
5-static-assets
6-form-session 

Switching To A Different Primer Section

Switch to the appropriate tag in the repository to show the code for a section.

Git CLI Example:

$ git reset --hard 1-hello-world
HEAD is now at e1be601 Hello World

GitHub Repository Example:

https://github.com/aenglander/lvpython-flask-talk/compare/1-hello-world...2-variable-routes

Seeing the Code Changes

You can view the code changes between primer sections using diffs of the tags.

Git CLI Example:

$ git diff 1-hello-world 2-variable-routes
diff --git a/app.py b/app.py
index 07b952c..f489716 100644
--- a/app.py
+++ b/app.py
@@ -5,5 +5,9 @@ app = Flask(__name__)
 def hello_world():
     return 'Hello World!'
 
+@app.route('/hello/<noun>')
+def hello_noun(noun):
+    return 'Hello %s!' % noun
+
 if __name__ == '__main__':
     app.run(debug=True)

Primer Sections

Hello World

The tag 1-hello-world provides the basic code needed to create an HTTP response for a default route.

Variable Routes

The tag 2-variable-routes shows how to access data provided in the URL within the controller method for a route.

Jinja Templates

The tag 3-jinja-templates shows how to use Jinja templates to return HTML from your routes.

Reverse Routing for Links

The tag 4-reverse-routing-for-links shows how to dynamically reference route locations within a Jinja template for linking within your site.

Static Assets

The tag 5-static-assets shows how to reference static assets like CSS, JavaScript, and images within your Jinja templates.

Forms and Sessions

The tag 6-form-session shows how to process form data, use flash messages and a cookie based session to interact with the user across requests, and redirect after a POST request using reverse routing inside the controller.