the name of the array to unwind
(unwindField: StringAdd).self
(unwindField: StringFormat).self
(unwindField: ArrowAssoc[UnwindField]).x
(Since version 2.10.0) Use leftOfArrow
instead
(unwindField: Ensuring[UnwindField]).x
(Since version 2.10.0) Use resultOfEnsuring
instead
Turns a document with an array into multiple documents, one document for each element in the array. http://docs.mongodb.org/manual/reference/aggregation/unwind/#_S_unwind