reactivemongo.api.commands.AggregationFramework
The fields to aggregate on, and the names they should be aggregated under.
the sequence of operators specifying aggregate calculation
(Since version 0.20.3) No longer a case class
(Since version 0.20.3) No longer a case class
(Since version 0.20.3) No longer a case class
$groups documents together to calculate aggregates on document collections. This command aggregates on multiple fields, and they must be named.