Question
Tata Consultancy Services
IN
Last activity: 25 May 2025 1:18 EDT
Does declare expression update values for existing cases
If I create a declare expression for an property(Say sum of properties) in a case , does the property value in all the existing cases get updated too?
***Edited by Moderator Marije to change type from Pega Academy to Product***
Capgemini
IN
The value of a declare expression target property changes only when the source properties is changing(forward chaining)
Hence, Lets consider below :
For an existing case value of Property1 is 10 and value of Property2 is 20
Now you decided to introduce Property3 and configure a declare expression for it to be sum of Property1 and Property2.
The value for Property3 will be blank initially for existing case.
But if you update the value for any of the source property change i.e. lets say Property2 is updated to 30 then property3 will become 40 as per declare expression.
Hope it helps!
Thanks, Ankit
Tata Consultancy Services
IN
@im-ankit Hi Ankit ,
Thanks for the reply . But i have different doubt , For instance in a data type whenever we create a new field and mention its value as calculated function and define a expression in advanced section (field3 = field1 + field2 ) it creates a declare expression in the Back end and all the new field values get populated . How does the logic work in this scenario ?
Capgemini
IN
Im also not sure about this behaviour for data class but from pattern I can see this is an example of chaining. I.e. case properties follow backward chaining which means target is refreshed while it is referenced.
Data table calculated field seems to follow forward chaining pattern which means target is refreshed when source property is updated.
Although Pega has removed options to mention chaining type on declare expression rule from Pega 8, but it seems to follow it at backend. I need to read more on this.
Maantic Inc
IN
If in the existing cases if the value of any of the properties comprising of the sum gets updated, then the declare expression will also trigger and update the result of the sum.