Using Overpass API find ways inside multipolygon relations

Question

I'm trying to find all buildings in ways AND relations, type=multipolygon. The code below works but only finds buildings in ways but not in the relation, type=multipolygon for 'landuse=military'. I know how to output the rel[landuse=military], but not how to feed those relations nodes into the is_in with the ways nodes.

[out:json];
(

way[landuse=military]({{bbox}});

);

node(w);is_in;
area._[landuse=military];
(
     way(area)[building];
     node(w);
);
out;

Answer 1

I would suggest a completely different approach:

[out:json]
[bbox:{{bbox}}];

( way[landuse=military];
  rel[landuse=military]; );
map_to_area;
way(area)[building];
out geom;

Try it in overpass turbo: http://overpass-turbo.eu/s/sJa

way + rel + map_to_area effectively returns all landuse=military areas in your bounding box, but since area[landuse=military] doesn't support a bbox filter, we have to take this slightly more complicated approach.

Take particular note that map_to_area is subject to area creation rules, which typically means that your area needs to have a name=* tag. Otherwise no respective area exists on the server. This behavior is documented as such, and not a bug.