Deno KV secondary index

db.js

export async function setUser(user) {
  const primaryKey = ["users", user.id];
  const byColorKey = ["users_by_favorite_color", user.favoriteColor, user.id];
  
  const oldUser = await getUser(user.id);
  
  const atomic = kv.atomic();

  if (oldUser) {
    if (oldUser.favoriteColor !== user.favoriteColor) {
      atomic.delete(byColorKey);
    }
  }

  await atomic
    .set(primaryKey, user)
    .set(byColorKey, user)
    .commit();
}