columnsNamed method

Map<String, Object?> columnsNamed(
  1. TRow row,
  2. Iterable<String> names
)

The named columns of row, and nothing else.

Relation grouping only needs the key columns. Building the whole row map to pick two names out of it is the allocation this avoids.

Implementation

Map<String, Object?> columnsNamed(TRow row, Iterable<String> names) =>
    <String, Object?>{for (final name in names) name: readColumn(row, name)};