reactivemongo.api.commands.AggregationFramework
the name of the field to aggregate on
the sequence of operators specifying aggregate calculation
the name of the field to aggregate on
(groupField: StringAdd).self
(groupField: StringFormat).self
(groupField: ArrowAssoc[GroupField]).x
(Since version 2.10.0) Use leftOfArrow
instead
(groupField: Ensuring[GroupField]).x
(Since version 2.10.0) Use resultOfEnsuring
instead
$groups documents together to calculate aggregates on document collections. This command aggregates on one field.
the name of the field to aggregate on
the sequence of operators specifying aggregate calculation