getCountByFilterEx method Null safety

Future<int> getCountByFilterEx(
  1. String? correlationId,
  2. Function? filter
)

Gets a count of data items retrieved by a given filter.

This method shall be called by a public getCountByFilter method from child class that receives FilterParams and converts them into a filter function.

  • correlationId (optional) transaction id to trace execution through call chain.
  • filter (optional) a filter function to filter items Return Future that receives a data count Throw error.