get_registry_record errors even if default value is given

[fredvd]

expected behavior:

When I query a record that is not yet loaded in the registry by running an upgrade step which reads in registry records defined by xml or a zope.schema interface, I should receive a default parameter if I passed that into the get_registry_record function call

What happens:

plone.api/src/plone/api/portal.py

Lines 299 to 306 in a8361ed

	if interface is not None:
	records = registry.forInterface(interface)
	_marker = object()
	if getattr(records, name, _marker) != _marker:
	return registry['{0}.{1}'.format(interface.__identifier__, name)]
	if default is not MISSING:
	return default

The function already errors on L300 when the forInterface() call cannot find my schema, L305 is never reached in this case.

  Module plone.api.portal, line 2, in get_registry_record
  Module plone.api.validation, line 77, in wrapped
  Module plone.api.portal, line 300, in get_registry_record
  Module plone.registry.registry, line 78, in forInterface
KeyError: 'Interface `myproject.content.interfaces.IProjectSettings` defines a field `somefield`, for which there is no record.'

[fredvd]

Whoops, wrong assumption. My IProjectSettings was already loaded in the registry, but I added a new field. And plone.registry.forInterface is checking if all fields from the Interface are loaded in the registry, which is not the case.

My suggested solution would be to pass 'check=False' to the forInterface call on L300, which will skip the field verification:

https://github.com/plone/plone.registry/blob/3d5c54a8cb100f882d0b4fa592f86a16a5cfba4e/plone/registry/registry.py#L67-L79

But this will throw a KeyError next on L303 , so that would have to be Exception handled as well. Nasty stuff.

[djay]

@fredvd I think what it needs is modifed records proxy that returns the schema defaults if the data is missing

[djay]

@fredvd I created a fix for the same problem in the restapi. it probably needs a similar fix here, or a combined fix somewhere else - plone/plone.restapi#1736