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How to customize a LookupList-based Dynamic Select control

Summary

You can use a Dynamic Select control to present an HTML drop-down list for an input field. See How to configure a Dynamic Select control (V4.2) for general information..

In many cases, the Dynamic Select control calls a standard activity named LookupList to create the field. This activity has special behavior: it stores its results in an XML file on disk (on the server), thereby creating a disk-based cache. The second and later time it runs, the previously saved results are retrieved from the cache rather than re-accessing the PegaRULES database.

In certain cases, you can customize the list, while still taking advantage of the performance benefits that using the LookupList cache provides.

Example

The View Queue for drop-down list in the "My Group" gadget in the portal is implemented by a Dynamic Select control backed by a LookupList.



 

Suggested Approach

When a Dynamic Select control uses a LookupList, the activity specified in the dssource tag contains the string "LookupList." To customize the contents of the displayed list, you can replace the LookupList activity with a custom activity. This custom activity can do the following:

  1. Call the currently used LookupList activity, instructing it to place the results on a clipboard page of class Code-Pega-List.
  2. Update the contents of the pxResults property on the Code-Pega-List page to reflect the desired list contents. (For example, you might remove elements from the list).
  3. Use the Show-Page method to send the modified Code-Pega-List page to the client workstation.

This approach works only if the results of the standard LookupList activity contain all the information you need for your modifications.

For example, if you need to filter the initial results based on a property that is not returned by the standard LookupList activity, then you cannot use this approach. You can still use a custom activity to provide list results, but that activity cannot use a LookupList as a starting point. Instead, your activity needs to fetch the list results directly from the database, and you would not achieve the performance benefits that LookupList provides.

Do not attempt to create or modify a LookupList activity.

Related topics

How to configure a Dynamic Select control (V4.2)

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Published January 26, 2005 — Updated December 20, 2005

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