Using Caché Objects - InterSystems Documentation

For example, the following code opens an instance of Sample.Employee object and automatically
(swizzles) opens its related Sample.Company object by referring to it using dot syntax:
// Open employee "101"
Set emp = ##class(Sample.Employee).%OpenId(101)
// Automatically open Sample.Company by referring to it:
Write "Company: ",emp.Company.Name,!
When an object is swizzled, it is opened using the default concurrency value of Atomic (see
next section). If you wish to change the concurrency level of a swizzled object use the
%UpgradeConcurrency and %DowngradeConcurrency methods.
A swizzled object is removed from memory as soon as no objects or variables refer to it.
12.2.2.4 Concurrency
The %OpenId method takes an optional concurrency argument as input. This argument
specifies the concurrency level (type of locks) that should be used to open the object instance.
For more information on the possible object concurrency levels, refer to Object Concurrency.
If the %OpenId method is unable to acquire a lock on an object, it will fail.
You can raise or lower the current concurrency setting for an object using the %Persistent
class' %UpgradeConcurrency and %DowngradeConcurrency methods, respectively.
12.2.2.5 Reloading an Object from Disk
If you wish to reload an in-memory object with the values stored within the database, you
can use the %Reload method provided by the %Persistent class.
// 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 reload the object from disk
Do person.%Reload()
Write "Reloaded value: ",person.Name,!
12.2.2.6 Reading Stored Values
The Persistence Interface
Suppose you have opened an instance of a persistent object, modified its properties, and then
wish to view the original value stored in the database before saving the object. The easiest
way to do this is to use an SQL statement (SQL is always executed against the database; not
against objects in memory).
Using Caché Objects 105