How to create entity relationships in slick? - scala

Question

I am working in a project with scala play 2 framework where i am using slick as FRM and postgres database.
In my project customer is an entity. So i create a customer table and customer case class and object also. Another entity is account. The code is given bellow
case class Customer(id: Option[Int],
status: String,
balance: Double,
payable: Double,
created: Option[Instant],
updated: Option[Instant]) extends GenericEntity {
def this(status: String,
balance: Double,
payable: Double) = this(None, status, balance, payable, None, None)
}
class CustomerTable(tag: Tag) extends GenericTable[Customer](tag, "customer"){
override def id = column[Option[Int]]("id")
def status = column[String]("status")
def balance = column[Double]("balance")
def payable = column[Double]("payable")
def account = foreignKey("fk_customer_account", id, Accounts.table)(_.id, onUpdate = ForeignKeyAction.Restrict, onDelete = ForeignKeyAction.Cascade)
def * = (id, status, balance, payable, created, updated) <> ((Customer.apply _).tupled, Customer.unapply)
}
object Customers extends GenericService[Customer, CustomerTable] {
override val table = TableQuery[CustomerTable]
val accountTable = TableQuery[AccountTable]
override def copyEntityFields(entity: Customer, id: Option[Int],
created: Option[Instant], updated: Option[Instant]): Customer = {
entity.copy(id = id, created = created, updated = updated)
}
}
Now the problem is how can i create an account object inside the customer object? Or how can i get the account of a customer?

Answer 1

Slick is not ORM its just a functional relational mapper. Nested objects cannot be directly used in slick like Hibernate or any other ORMs Instead
Slick
//Usual ORM mapping works with nested objects
case class Person(name: String, age: Int, address: Address) //nested object
//With Slick
case class Address(addressStr: String, id: Long) //id primary key
case class Person(name: String, age: Int, addressId: Long) //addressId is the id of the address object and its going to the foreign key
Account object in Customer
case class Account(id: Long, ....) // .... means other fields.
case class Customer(accountId: Long, ....)
Place accountId inside the Customer object and make it a foreign key
For more info refer to Slick example provided as part of documentation