Using Caché Objects - InterSystems Documentation

Object Persistence
For example:
// Open person "1"
Set person = ##class(Sample.Person).%OpenId(1)
Write "Original value: ",person.Name,!
// modify the object
Set person.Name = "Black,Jimmy Carl"
Write "Modified value: ",person.Name,!
// Now see what value is on disk
Set id = person.%Id()
&sql(SELECT Name INTO :name
FROM Sample.Person WHERE %ID = :id)
Write "Disk value: ",name,!
12.2.3 Deleting Objects
The Persistence Interface includes several methods for deleting objects from the database.
12.2.3.1 The %DeleteId Method
The %DeleteId method deletes a an object that is stored within a database:
Set sc = ##class(MyApp.MyClass).%DeleteId(id)
%DeleteId returns a %Status value indicating whether the object was deleted or not.
If present, %DeleteId will call the %OnDelete callback method before deleting the object.
%OnDelete returns a %Status value; if %OnDelete returns an error value, then the object
will not be deleted, the current transaction is rolled back, and %DeleteId returns an error
value.
Note that the %DeleteId method is a class method and has no effect on any object instances
that may be in memory.
12.2.3.2 The %DeleteExtent Method
The %DeleteExtent method deletes every object (and subclass of object) within its extent.
Specifically it iterates the entire extent of objects and then invokes the %DeleteId method
on each instance.
12.2.3.3 The %KillExtent Method
The %KillExtent method directly deletes the globals used to store an extent of objects. It
does not invoke the %DeleteId method and performs no referential integrity actions. This
method is simply intended to serve as a help to developers during the development process.
106 Using Caché Objects