Class form
Completing the External Mapping tab

5.5 The External Mapping tab is used primarily for external classes (classes created by the Connector and Metadata accelerator rXXXXXXXXXXXX and linked by a Database Table data instance to a table in an external database.)

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Ordinarily, this tab is completed by the Connector and Metadata accelerator and no changes are required. Note the special case described below.

Field	Description
External Table Column Mapping	Optional. Leave blank unless this class is an external class that represents a table in an external database (generated by the Connector and Metadata Accelerator), or you are replicating scalar embedded properties as described below. BUG-5356 and CODE-215 Fields in this section map the property rules generated for the class rule to the columns in the external table. See About generating connectors with the Connector and Metadata accelerator.
Column Name	For generated class rules, the name of a column in the external table. PROJ-616
Property Name	For generated class rules, the name of the property rule that represents the table column in the Column Name field. BUG-3276

Exposing an embedded Single Value property value into a column

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For a concrete internal class, you can use this tab to expose match an embedded Single Value property in a database column. WERDA/CLINB/BIXBS 11/17/09

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

About Class rules