Ghent critical issue sprint recap

Last month, 13 sprinters gathered in Ghent, Belgium for a very focused sprint designed to accelerate work on issues blocking the release of Drupal 8. The sprint was a great burst of momentum for the core critical queue -- we went from 115 critical issues at the start of the sprint to only 81 as of today. That means we have 30% fewer critical issues than we did a month ago.

During the 5-day sprint, we worked on an impressive 51 critical issues, 28 of which are already fixed. Of particular note are the 18 upgrade path blockers that we moved forward (that's 70% of the issues blocking a beta-to-beta upgrade path during that time).

Sprint goals: Accomplished!

Before the sprint, we set some goals for the progress we wanted to make on upgrade path blockers for the Entity Field API, Configuration system, and Views. Here's how we did on each of these goals:

Views data structure and Entity Field API integration

We decoupled Views' entity field data from the SQL table structure by storing entity field information in the view configuration. This will make it possible for Views to detect when the entity field schema has changed and respond to the changes (as well as allowing better support for non-SQL databases). We also defined the entity schema changes that Views will need to support, and work is underway to support them.

Content and configuration dependencies in Views

We added content and configuration dependencies to Views so that Views that use entity display modes, field formatters, user roles, and so on can be safely deployed. We also discussed how to store deployable references to entities (for example, the taxonomy term displayed at the top of taxonomy/term/* listings) based on the shared needs of Views and Entity Reference. A patch to implement the proposed API in Views is nearly ready.

Global settings.php overrides

We had a fruitful discussion that clarified the problem space and culminated in splitting the issue into two steps. We retitled and resummarized the original issue into the second step, and began work on the first step. While getting an initial patch for the first step to pass tests, we uncovered several blocker issues, each of which has now been committed. The patch for this issue is now up for review.

Configuration schema

All hidden configuration schema issues are now fixed and will not regress, because all tests now have strict schema checking enabled by default!
To help people get started with config schemas, Gábor Hojtsy also created a very handy cheat sheet that provides the most crucial information at a glance.

Data integrity on module uninstallation

The two critical bugs in this problem space are now fixed:

Modules that define content entity types (e.g., node.module, comment.module) can no longer be uninstalled if the site has existing entities of that type. Instead, the site administrator must first delete the entities via normal channels (UI, Drush, etc.), so that deletion hooks and the corresponding reference cleanups happen.
Modules that define field storages (e.g., path.module) can no longer be uninstalled if the site has existing entities with data for that field. Instead, the site administrator must first either delete those entities or update them to have empty values for that field.

To implement both of the above, we created a new ModuleUninstallValidatorInterface. We also have a non-critical issue to better integrate those validators when a module is being uninstalled as part of a configuration import.

NOT NULL constraints for entity base fields

Thanks to fast collaboration between plach, amateescu, yched, and fago (which was greatly assisted by having them all together in-person), a patch that fixes the fatal error bug has now been committed. This required resolving some trickiness with entity reference fields, whose target_id property is simultaneously required but not known while in the process of referencing a not-yet-saved entity. The solution results in a more semantically correct API and better delineation of responsibilities between field types, field definitions, and storage handlers for identifying and implementing required-ness.

The UN of Chocolate

We worked hard at the sprint, but also managed to fit in some international chocolate comparisons, with Swiss, Hungarian, and Belgian sweets to power all that coding. Contributor pfrenssen also pledged not to shave until 8.0.0 (1 cm of beard per beta?), and Berdir shared just how brimming with criticals his issue tracker became. We even learned a bit about the history of Ghent, thanks to swentel and his father-in-law.