Django Unleashed

10.4 Schema Migrations

Creating data migrations are a nice introduction to migrations, but they may be a little too simplistic, mainly because they always rely on a single operation: RunPython. Django offers 15 others, and while we won’t have the opportunity to see all of them, we are now forced to use some of them to fix a few problems our site has.

When creating NewsLinkUpdate (Chapter 9, Section 9.3.2) and NewsLinkDelete (Chapter 9, Section 9.4.2) we discovered that we needed a unique way to identify NewsLink objects. At the moment, we’re using the primary key of each instance, a practice that is frowned upon because it leads to human-unfriendly URLs. Building NewsLink without a SlugField was thus (intentionally) a mistake that we need to ...