# How to reference a collection from another collection?

1. Define the property as reference in the collection. For example:

   
   
   
   
   
   
   
   
   
   

    

   
   
   

   collection Address {
   	property line1:String
   	property line2:String
   	property city:String
   	property state:String
   }
   collection Employee {
   	property name:String
   	property designation:String
   	reference address:Address
   }
   

2. enter sbt shell, run command compile

   Note: In terms of the fields in the collection, only the object Id of the referenced collection is stored. For example: address is stored address_oid inside employee collection

# Sample Usage:

//Create
def addEmployee(): Unit = {
  val addressRow = AddressRow(_id = new Id,
  	line1 = "No 123, 4th Street", city = "Bangalore", state = "Karnataka")
  AddressWriter().insert(addressRow)

  val empRow = EmployeeRow(
  	name = "Vivitsa", designation = "HR",
  	address_oid = addressRow._id)
  EmployeeWriter().insert(empRow)
}

//Read
def getResidentCity(employeeId:Id):String = {
    val empRow = EmployeeQuery.findById(employeeId).get
    empRow.address.city
}