orderBy method
Returns FireDartCollectionReference that's additionally sorted by the specified
fieldPath.
The field is a String representing a single field name. After a FireDartCollectionReference order by call, you cannot add any more orderBy calls.
Implementation
FireDartQueryReference orderBy(String fieldPath, {bool descending = false}) =>
FireDartQueryReference(gateway, path)
.orderBy(fieldPath, descending: descending);