Using Caché Objects Defining and Using Object-Valued Properties [Home] [Back] [Next]

• How to define object-valued properties
• Introduction to serial objects
• Possible combinations of objects
• How to specify the value of an object property
• How to save changes
• SQL projection of object-valued properties (for persistent classes)

Property PropName as Classname;

Class MyApp.CurrencyOrder [ NoExtent ] 
{
Property Payment as MyApp.CreditCard (CLASSNAME=1);

//other class members
}

• It is not necessary to call %New() to create the serial object before assigning values to properties in it.
• If the serial object property is contained in a persistent class, the properties of the serial object are stored within the extent of the persistent class.

Class Sample.Address Extends %SerialObject
{

/// The street address.
Property Street As %String(MAXLEN = 80);

/// The city name.
Property City As %String(MAXLEN = 80);

/// The 2-letter state abbreviation.
Property State As %String(MAXLEN = 2);

/// The 5-digit U.S. Zone Improvement Plan (ZIP) code.
Property Zip As %String(MAXLEN = 5);

}

• Reference properties (properties based on other persistent objects)
• Embedded object properties (properties based on serial objects)

Class MyApp.ClassA
{

Property PropB as MyApp.ClassB;

//additional class members
}

1. If ClassB is not a serial class, first:
   1. Obtain an OREF for an instance of ClassB.
   2. Optionally set properties of this instance. You can also set them later.
   3. Set MyClassAInstance.PropB equal to that OREF.
   You can skip this step if ClassB is a serial class.
2. Optionally use cascading dot syntax to set properties of the property (that is, to set properties of MyClassAInstance.PropB).

 set myclassBInstance=##class(MyApp.ClassB).%New()
 set myClassBInstance.Prop1="abc"
 set myClassBInstance.Prop2="def"
 set myClassAInstance.PropB=myclassBInstance
 set myClassAInstance.PropB.Prop3="ghi"

 set myClassAInstance.PropB=##class(MyApp.ClassB).%New()
 set myClassAInstance.PropB.Prop1="abc"
 set myClassAInstance.PropB.Prop2="def"
 set myClassAInstance.PropB.Prop3="ghi"

 set myClassAInstance.PropB.Prop1="abc"
 set myClassAInstance.PropB.Prop2="def"
 set myClassAInstance.PropB.Prop3="ghi"

Class MyApp.Customers Extends %Persistent
{

Property Name As %String;

Property HomeStreet As %String(MAXLEN = 80);

Property HomeCity As MyApp.Cities;

}

Class MyApp.Cities Extends %Persistent
{

Property City As %String(MAXLEN = 80);

Property State As %String;

Property ZIP As %String;

}

    set customer=##class(MyApp.Customers).%New()
    set customer.Name="O'Greavy,N."
    set customer.HomeStreet="1234 Main Street"
    set customer.HomeCity=##class(MyApp.Cities).%New()
    set customer.HomeCity.City="Overton"
    set customer.HomeCity.State="Any State"
    set customer.HomeCity.ZIP="00000"
    set status=customer.%Save()
    if $$$ISERR(status) {
        do $system.Status.DisplayError(status)
    }

    set customer=##class(MyApp.Customers).%New()
    set customer.Name="Burton,J.K."
    set customer.HomeStreet="17 Milk Street"
    set customer.HomeCity=##class(MyApp.Cities).%OpenId(3)
    set status=customer.%Save()
    if $$$ISERR(status) {
        do $system.Status.DisplayError(status)
    }

    set customer=##class(MyApp.Customers).%New()
    set customer.Name="Emerson,S."
    set customer.HomeStreet="295 School Lane"
    set customer.HomeCity=##class(MyApp.Cities).%OpenId(2)
    set customer.HomeCity.ZIP="11111"
    set status=customer.%Save()
    if $$$ISERR(status) {
        do $system.Status.DisplayError(status)
    }

SELECT Company->Name FROM Sample.Employee ORDER BY Company->Name

SELECT Name, Home_City, Home_State FROM Sample.Person 
WHERE Home_City %STARTSWITH 'B'
ORDER BY Home_City

• The projection of a reference property includes a read-only field that includes the object reference as described in “Reference Properties.”
• The projection of an array is as a single, non-editable column that is part of the table.
• The projection of a list is as a list field as one of its projected fields; the list field is as described in “Default Projection of List Properties.”