Resources, Hierarchies, and Traversal

Web applications have URLs which locate data and make operations on that data. Pyramid supports two ways of mapping URLs into Python operations:

• The more-traditional approach of URL dispatch aka routes
• The more object-oriented approach of traversal popularized by Zope

As this is a tutorial at the Plone Conference, we will show building an application using traversal. Along the way, we will try to show how easy and Pythonic it is to think in terms of traversal.

Remember...traversal is easy, powerful, and useful.

With traversal, you think of your website as a tree of Python objects, just like a dictionary of dictionaries. For example:

http://example.com/company1/aFolder/subFolder/doc1/add?x=1

...is nothing more than:

>>> root['aFolder']['subFolder']['doc1'].add(x=1)

Goals

• Easiest possible introduction to traversal
• A tree of resources of different “types”
• Show how views can be specific to a certain “type”
• Integrate back into our ongoing application

Contents

• Step 01: Most Basic Resource: Site Root
• Step 02: Basic Hierarchy for Traversal
• Step 03: Type-Specific Views
• Step 04: Creating Basic Content
• Step 05: Projector with Resources