Using Caché Objects - InterSystems Documentation

Unless otherwise configured, Caché uses random data to populate the class. In cases with
defined constraints, such as a minimum or maximum length, some of the generated data may
not pass validation, so that individual objects will not be saved. In these situations, Populate
may create fewer than the specified number of objects. To allow you to check this, Populate
returns the number of objects actually populated:
Set objs = ##class(Person).Populate(100)
// objs is set to the number of objects created.
// objs will be less than or equal to 100
The populate utility is aware of the MAXVAL and MINVAL parameters and automatically
creates data that obeys these conditions for properties of type %Integer.
19.1.2.1 Object-valued Properties
The populate utility can automatically generate values for object-valued properties —
embedded objects as well as references to other persistent objects. This allows you to test or
demonstrate more complex objects and classes.
To enable population for these properties:
1. Include %Populate among the superclasses of the referenced class.
2. Create one or more instances of the referenced class.
The POPSPEC Parameter
This ensures that there are valid objects for the object-valued properties to point to.
19.2 The POPSPEC Parameter
The populate utility can provide data for properties containing embedded objects, lists, arrays,
and combinations of these with object-valued properties; it also allows you to customize the
data of certain data type properties.
To perform this kind of data population, provide a value for a property's POPSPEC parameter
by having it reference a method for generating data. If POPSPEC has a value, then the
Populate method invokes the referenced method to generate a value for the property. This
method can be user-provided or one of the methods of the %PopulateUtils class (provided
within the Caché library). Methods of %PopulateUtils provide data such as the names of
people, states, countries, or street address in the United States. Refer to the class' documentation
for a complete list of available methods.
To use POPSPEC, set its value as part of a property definition, as follows:
Using Caché Objects 163