Problem/Motivation
Right now, when you complete a Drupal 8 migration, AFAICS in all cases, you get your node/comment titles moved over, but the bodies display as blank:
The data for the fields is in the database, but getting stripped out on the front end.
According to the migrate team, this happens when filter formats not recognized by Drupal 8; they get migrated as filter_null, a filter that simply returns an empty string. However, to an "end user" it just appears that migrations don't work, even for very simple core cases where no fancy non-core input formats were used.
Major/Migrate critical because this represents a pretty significant usability hurdle, and harms user confidence in the system early on.
Proposed resolution
Instead, map mismatched filter formats to fallback_format (defaults to plain text).
The one possible reason not to do this is PHP code filter, where you could inadvertently expose database credentials that would now be exposed in plain text. However, we could probably deal with this case specially. (For example, explicitly setting that one to filter_null to indicate it needs attention.)
Remaining tasks
- Write a patch + tests
- Review it
- Commit it!
User interface changes
By default, migrations will now display at least something for body field content for nodes and comments. (As well as other rich text fields.)
API changes
?
Data model changes
N/A?
Release notes snippet
Migrations now default to the fallback filter format, fixing a problem where rich text fields were not displaying post-migration.