Question
Stella
US
Last activity: 3 Oct 2019 15:09 EDT
Declarative Expressions
When will a declare expression be triggered when it is set to "Whenever inputs change"? I have declarative expression on embedded property populated by a report definition. My declarative expression does not fire. The reason I was given was this :
"fetching the data from the DB and not changing the value so it is not considering the value to be changed."
If I create an activity and create a page and set a value on a property on that page that my declare expression is dependent on the expression fires. What is the difference? Why won't declare expressions fire when properties it is dependent on get populated by report definition?
***Edited by Moderator Marissa to update platform capability tags; update SR details****
Pegasystems Inc.
US
Whenever input changes, target property gets calculated.
Eg: Total price = Cost * Quantity
Here, whenever Cost or Quantity change Declare expression fire and Total price gets calculated based on the expression in the declare expression rule.
It will only get fired if the value of input changes(fetching the data from DB and putting in property in memory does not mean the value is changed). Please correct me if I am wrong anywhere.
Stella
US
So if I change the declare expression to whenever used and display the property on the UI it then does fire. If I have a declare expression based on the value of that property and set to whenever inputs changed why does that property not get calculated when the other property gets calculated?
Stella
US
Before I call the report def I don't have anything on the clipboard but when I call the report def it now creates "properties" on the clipboard. Or am I thinking of it wrong here. What is on the clipboard are really not properties unless it gets posted back to the server and sets actually properties?
Pegasystems Inc.
US
If you select "Whenever inputs change" in the Compute Values field, then each time the value of any property referenced in any Declare Expression rule — or properties in other rules (such as decision trees, decision tables, or map values) referenced in the Declare Expression rule — changes, the system computes the values of the target property.
If the Declare Expression rule contains a non-blank Page Context field, the expression is evaluated at run time only when the clipboard contains a page matching that full context.
For more detailed information about Declarative Expression, please check below pdn link: