A database layer is implemented in terms of the Doobie library. Each entity has a separate Scala file, where there is a singleton object, which has all of the methods that we need for the purposes of this application. For example, let's take a look at the API that the customer object exposes:
object customer extends CustomerDbHelpers { def create(c: Customer): IO[Int] = ??? def findByName(name: String): IO[Option[Customer]] = ??? def list: IO[List[Customer]] = ??? def get(id: Int): IO[Customer] = ??? def update(c: Customer): IO[Int] = ??? def delete(id: Int): IO[Int] = ???}trait CustomerDbHelpers { val selectCustomerSql = fr"select * from customer" // to be explained further in the chapter}
So, we have several database access ...
