Project: QGIS

Version: 3.0.0

Feature: Expose @parent variable in aggregate functions

This makes it possible to access attributes and geometry from the parent feature when in the filter of the "aggregate" expression function. With this in place aggregates can be calculated per feature.

E.g. max "measurement" for each point_station per polygon_research_area.

Or a default attribute value when digitizing features:

aggregate(layer:='countries', aggregate:='max', expression:=\"code\", filter:=intersects( $geometry, geometry(@parent) ) )

This feature was developed by Matthias Kuhn (OPENGIS.ch)