Using Caché Objects - InterSystems Documentation

An Invoice class
class MyApp.Invoice Extends %Persistent [ClassType = persistent]
{
Property CustomerName As %String;
/// an Invoice has CHILDREN that are LineItems
Relationship Items As LineItem [inverse = TheInvoice, cardinality = CHILDREN];
}
and LineItem:
/// A LineItem class
class MyApp.LineItem Extends %Persistent [ClassType = persistent]
{
Property Product As %String;
Property Quantity As %Integer;
In-Memory Behavior of Relationships
/// a LineItem has a PARENT that is an Invoice
Relationship TheInvoice As Invoice [inverse = Items, cardinality = PARENT];
}
14.3 In-Memory Behavior of Relationships
Programmatically, relationships behave as properties. Single-valued relationships (cardinality
of “ONE” or “PARENT” ) behave like atomic (non-collection) reference properties. Multivalued
relationships (cardinality of “MANY” or “CHILDREN” ) are instances of the
%RelationshipObject class which has a collection-like interface.
For example, you could use the Company and Employee objects defined above in the following
way:
// create a new instance of Company
Set company = ##class(Company).%New()
Set company.Name = "Chiaroscuro LLC"
// create a new instance of Employee
Set emp = ##class(Employee).%New()
Set emp.Name = "Weiss,Melanie"
Set emp.Title = "CEO"
// Now associate Employee with Company
Set emp.TheCompany = company
// Save the Company (this will save emp as well)
Do company.%Save()
// Close the newly created objects
Do company.%Close()
Do employee.%Close()
Relationships are fully bi-directional in memory; any operation on one side is immediately
visible on the other side. Hence, the code above is equivalent to the following, which instead
operates on the company:
Using Caché Objects 129