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GitHub User: jbbarth
Fyi, the mongoid_ancestry gem provides nearly the same feature set as the ancestry gem for active_record, but for mongoid. It has some gotchas but worth to check out.
This lib is amazing, thanks for this screencast. Note that #arrange method does not work perfectly if you have a too recent activerecord and an order clause in your default_scope's model. See the issue on github if needed ( https://github.com/stefankroes/ancestry/issues/42 ).