TopoElement — Converts a topogeometry to a topoelement.
topoelement TopoElement(topogeometry topo);
This is a full self-contained workflow
Return the TopoElement representation of each topogeometry.
SELECT TopoElement(topo) FROM neighborhoods;
Use a cast to aggregate topogeometries into a TopoElementArray.
SELECT topology.TopoElementArray_Agg(topo::topoelement) FROM neighborhoods GROUP BY city;