Skip to main content


         This documentation site is for previous versions. Visit our new documentation site for current releases.      
 

This content has been archived and is no longer being updated.

Links may not function; however, this content may be relevant to outdated versions of the product.

More about Decision Trees

Updated on March 11, 2021

Overriding the property

Decision tree evaluation may be based on a known property identified on the Configuration tab, or on a parameter supplied in the Property-Map-DecisionTree method, or both.

If you leave the Property field blank, evaluation is always based on the parameter. If a parameter is supplied, the parameter value is used even when the Property field is not blank.

Standard functions

As an alternative to the Property-Map-DecisionTree method, you can use these standard functions to evaluate a decision tree:

@(Pega-RULES:DecisionTree).ObtainValue(tools, myStepPage, decisiontree, inputproperty)
@(Pega-RULES:DecisionTree).ObtainValue(tools, myStepPage, decisiontree, inputproperty, bAllowMissingProperties)

Decision tree rules can also be evaluated as part of a collection rule ( Rule-Declare-Collection rule type).

Pega Community note

See the Pega Community article How to evaluate a decision tree and handle errors for an example.

Uploading a text file to start

You can create a decision tree by importing (or "harvesting) a specially formatted text file. This capability lets others not familiar with the Pega Platform create decision trees.

Performance

The number of nodes in a decision tree is not limited. However, as a best practice to avoid slow performance when updating the form and also avoid the Java 64 KB code maximum, limit your decision trees to no more than 300 to 500 rows.

You can view the generated Java code of a rule by clicking ActionsView Java. You can use this code to debug your application or to examine how rules are implemented.

Special processing with Declare Expression calls

When a Declare Expression rule has Result of decision tree for the Set Property To field, special processing occurs at runtime when a property referenced in the decision table is not present on the clipboard. Ordinarily such decision rules fail with an error message; in this case the Otherwise value is returned instead. For details, see the Pega Community article Troubleshooting: Declarative Expression does not execute when a decision rule provides no return value.

Not declarative

Despite the class name, the Rule-Declare-DecisionTable rule type does not produce forward or backward chaining. Technically, it is not a declarative rule type.

Custom function aliases

You can use Configuration tab to enable custom function aliases instead of the default comparison. For some of those aliases, you can click Select values and select from a list of values that are available for the selected property.

Have a question? Get answers now.

Visit the Support Center to ask questions, engage in discussions, share ideas, and help others.

Did you find this content helpful?

Want to help us improve this content?

We'd prefer it if you saw us at our best.

Pega.com is not optimized for Internet Explorer. For the optimal experience, please use:

Close Deprecation Notice
Contact us