I am trying to automatically write the maximum (and minimum) value of a specific layers attribute (a date (or a number)) in qgis print composer.
I'm trying to do this for an automatically updated map and its title should automatically get the time range of events (for example "Earthquakes from 07/2016 to 09/2017"). Date of each event is stored in the attribute table of a layer (*.csv). Also each event has an ID starting by the oldest event (so max/min id would work as well). (Goal of all this is that users only need to press "export pdf" and nothing else)
Was trying to combine "attribute", "maximum", "get_feature" and "layer_property" in query builder in different ways. While it was no problem to do in attribute tables I wasnt able to figure out how it could work in print composer. Minimum works pretty simple this way
attribute(get_feature('own.earthquakes','valid','1'),'event_date')
So far I unfortunately have no experience with phyton.
Any ideas about this?