low_level_components.kt

server.addRoute("/customers/:id/companies", middlewares, ::customerCompaniesHandler)

fun customerCompaniesHandler(req: Request, res: Response) {
  val db = req.components.db
  val customerId = req.params.id;
  res.send(getCustomerCompanies(customerId, db) 
} 

fun getCustomerCompanies(customerId: Int, db: Database): List<Company> {
  val stocks = getStocks(customerId, db) 
  val companyIds = stocks.map { it.companyId }
  return companyIds.map { getCompanyById(it, db) } 
} 

fun getCompanyById(companyId: Int, db: Database) =
  CompanyStore.Db.Queries.companyById(id, db)