Class form
Understanding the External Mapping tab

Ordinarily, this tab is completed by one of these two tools, and no changes are required. The special case described below is an exception.

Exposing an embedded Single Value property value into a column

For a concrete internal class, you can use this tab to expose match an embedded Single Value property in a database column.

For example, the embedded property .pyPreferences.pyCaptionDisplay for a user who is a developer records a preference for whether that operator wants to see rule names, or Description text. (This property has one of the two values NAME or LABEL, as selected on the Preferences menu item, View group.)

If it was important to use this embedded property as report selection criteria, the property must correspond to a column. Use these steps to make a (scalar) embedded property available as a database column.

1. Ask a DBA to create a new column of the appropriate data type in the PegaRULES database table that corresponds to the Data-Admin-Operator-ID table. In this example, the table is pr_operators. The DBA created a text column named CAPTIONDISPLAY. (You can't use the Modify Schema wizard to add this column, because there is no property named CAPTIONDISPLAY.)
2. Update the Class rule for the class Data-Admin-Operator-ID. Add a row to the Column Mapping array on this tab. Enter the new column name CAPTIONDISPLAY the Column Name field and the embedded property reference in the Property Name field.
3. Thereafter, the system updates the new column CAPTIONDISPLAY from the embedded property .pyPreferences.pyCaptionDisplay whenever an Operator ID data instance is saved. The property reference pyPreferences.pyCaptionDisplay can be used as criteria in List View and Summary View reports.

This feature provides a direct but limited alternative to creating an Index- class and maintaining the index through a Declare Index rule, or to replicating the value to a second (top-level) property using a Declare Expression rule or Declare Trigger rule.

Notes:

• In contrast to a Declare Index approach, the embedded property must be a scalar reference, not an aggregate.
• You can use this approach to expose one fixed scalar value within an aggregate property, such as pyWorkparty(“Originator”).pyLastName for the last name of the Originator work party in a work item. In most situations, however, you want to expose all values, not a single value; the technique described here does not suffice.
• Like other schema changes, the DBA must add the column in every systems that contains the report rules (such as development, test, and production systems).
• You can update Class rules that belong to foundation RuleSets (for example, the Data-Admin-Operator-ID class)

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