Data properties (DATA)

Data property is a property which value is stored in the database and may change through the execution of the corresponding action. Each parameter and the value of a data property must belong to a certain specified class. If a parameter does not belong to the specified class or is NULL, then the property value will return NULL.

Local data properties

Data properties can be local. Such properties retain their values only within the session, i.e. they are not saved to the database, which means when applying changes these values are reset to NULL by default.

A regular local property is convenient as temporary storage inside one session or one interaction flow. If the value must survive session-management operations, the local property can be made nested.

Nested local data properties

A nested local data property is a local data property whose value is preserved by the platform during the required session-management operations.

The basic nested mode preserves the property value for all major session-management operations:

• when entering and leaving a new session;
• after applying changes;
• after canceling changes.

If preservation is required only for part of these operations, a restricted nested mode is used: either only for applying changes and canceling changes, or only when entering and leaving a new session.

Language

To declare a data property, use the DATA operator.

Examples

CLASS Item;
quantity = DATA LOCAL INTEGER (Item);

sessionOwners = DATA LOCAL NESTED MANAGESESSION INTEGER ();

CLASS Order;
selected = DATA LOCAL NESTED NOMANAGESESSION BOOLEAN (Order);

CLASS Country;
isDayOff = DATA BOOLEAN (Country, DATE);