cer 7.x-3.x-dev

This is a major refactoring/rewrite that includes the following improvements:

• Completely rewritten UI. Instead of a long, hard-to-read list of checkboxes, Hierarchical Select is now used to create CER relationships between fields, and it is a soft dependency if you want to use the UI at all. (Because CER's core functionality doesn't rely on Hierarchical Select, there are no plans to make it a hard dependency.)
• Support for field collections. 'Nuff said.
• Better error handling. No more of the CerExceptions that were rampant in the 2.x branch; if an error occurs, it is logged into watchdog along with readable information about the nature of the problem and the entities/fields involved.
• Native support for Entity Reference, Node Reference, User Reference, Taxonomy Term Reference and File/Image fields. You can create relationships between different kinds of fields, and CER will handle them transparently.
• Integration with Commerce Product Reference and Profile2 using bundled add-on modules.
• Upgrade path from Corresponding Node References. This version of CER will automatically take over from CNR if it's installed, and disable it.
• Rudimentary object-oriented API for extending CER's behavior with different field types and behavior. This is still very much a work in progress, though.

Regressions

Features integration is not yet supported. If you would like to contribute a patch for this, please feel free. If not, I'll get around to it eventually.

Caveats

• devel_generate does not play nicely with CER, and if you're using it, the results are unpredictable.
• i18n support is still flaky to nonexistent.
• Due to the way Commerce Product Reference fields work, CER relationships with such fields are "one-directional". This means that only changes to one side of the relationship will have any effect. For this reason, I don't recommend using CER to manage product references, although it's there if you need it for some reason.
• Clear all caches before running update.php! This version of CER introduces many new classes that need to be registered with the autoloader.

Roadmap

• We need full, proper test coverage.
• Reintroduce exportability/integration with Features.
• Rely on Entity API for low-level operations (currently, CER is partially reinventing the wheel).
• Aggressive performance optimization. I haven't done any profiling of CER, but I've got every reason to believe it is sloooow!

This is the active development branch, and it is possible to directly update to this version from either 1.x or 2.x, both of which should be considered obsolete.