Type casting

Type casting refines the results of a query and allows Rational® Publishing Engine to treat .xsd schema types as being from a different type, similar to cast operations in programming languages. A type is not assigned to schema elements that can have more than one valid type. You define the types for these elements with the cast to type feature in the Data source schema view.

About this task

Type casting works as an alternate filter for data source elements. A cast query filters the results of the regular query to return only the elements that can be cast to the selected type. After the type is selected, it becomes available in the Data Source Schema view under the anyType element. Queries built using cast allow access to all the child elements and attributes of the type cast. The result set returned by a cast query is identical to the result set returned by a query that is filtered with an equivalent IsKindOf predicate. The difference between the cast query and filtered query is that a cast query gives access to the cast type attributes and child elements while the filtered query does not.

Note: IBM® Rational Tau and IBM Rational Rhapsody® data sources support type casting.

Procedure

  1. Drag a Container icon Container element into the template content editor.
  2. From the Data Source Schema view, drag the ownedMember class into template.
  3. Name the container Class Container for quick reference.
  4. Click the Cast to Type icon icon and select the Class type cast for the ownedMember.
  5. Drag a Paragraph icon Paragraph element and place it below the container element, and add the name of the package inside the Class Container by dragging the Name(string) attribute.
  6. Drag a Text icon Text element to the template content editor.
  7. From the Data Source Schema view, drag the static text (Active) to the text element.
  8. Right-click the text element, and then click Data > Edit Condition.
  9. In the Set Condition for Current Element window, expand Attributes, and select the check box for IsActive attribute.
  10. For the Left operand , select IsActive.
  11. For the Operator, select Equals.
  12. For the Right operand, enter true.
  13. Click Add. The condition displays as: IsActive == "true"
  14. Click OK.

Results

Adding a Class cast to the ownedMember element of a package allows you to define the following query, which returns only the definitions that are classes from the same context:

Type Casting


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