from zope.app.appsetup.interfaces import IDatabaseOpenedWithRootEvent
from zope.app.appsetup.bootstrap import getInformationFromEvent

@adapter(IDatabaseOpenedWithRootEvent)
def addFoobar(event):

    db, connection, root, root_folder = getInformationFromEvent(event)

    if 'swarmfinder' not in root_folder:
        root_folder['foobar'] = Foobar()k