QGIS atlas print composer : aggregate (bigger overlap)

Question

With QGIS 3.30, In the composer interface, I generate an atlas. My iteration layer is polygonal layer (platforms). I added a text element to automatically get by spatial intersection the 'parcel_id' attribute present in another polygonal layer. I use the aggregate function for this task :

aggregate(
    'LAYER':='PARCEL_LAYER',
    aggregate:='concatenate',
    expression:="parcel_id",
    filter:=intersects(geometry(@parent), $geometry)
)

It works. But the result shows values of all the intersections. I would like it limit to the result of the biggest intersection. How can I do this?

Answer 1

Use overlay_intersect() function for that. In newer QGIS versions, it has an optional argument sort_by_intersection_size. So this should work:

concatenate( 
overlay_intersects(
        'PARCEL_LAYER',
        "parcel_id",
        sort_by_intersection_size:='des'
    )[0]
)