drools getting error : handle not found for object is it in working memory

Question

This question is in continuation to an earlier question here so my data structure is as earlier :

public class Premium{
  private List<InsuranceType> insuranceTypes;
  // getter and setter
  }

public class InsuranceType {
  private String name;
  private String category;
  // getter and setter
}

And here is my rule thanks to @RoddyoftheFrozenPeas

rule "Example"
when
  $pcr:Premium( $insuranceTypes: insuranceTypes )
  $ins:( InsuranceType( name == "TPD" , category == "D" ) from $insuranceTypes )      
then
  modify( $ins ){ 
        setCategory("A"); 
  }     
end

However when running this rule get an exception:

java.lang.RuntimeException: Update error: handle not found for object: InsuranceType [name=TPD, category=A]. Is it in the working memory?

Is this occurring because I am checking for the same attribute and also updating it ? My use case is to replace the value so I have to check for its presence ( category = D and then set it to 'A' )

Answer 1

InsuranceType is not in working memory -- Premium is. So you need to modify Premium, not insurance type.

There's really not a good way to do this. You could call update, but this will refire all rules (it's the equivalent of starting over with new data in working memory.)

then
  $ins.setCategory("A");
  update( $pcr );
end

This might cause side effects like looping or excessive rule triggers.

Alternatively you could modify the Premium by setting the List value:

then
  $ins.setCategory("A");
  modify( $pcr ){ 
    setInsuranceTypes($insuranceTypes)
  }     
end

... which is clunky but as long as we've not lost the reference to the list should do what we want.

---

Also, not entirely related, but the outer () are not necessary on your $ins declaration line. This is sufficient:

$ins: InsuranceType( name == "TPD" , category == "D" ) from $insuranceTypes

I think your original rule had an exists() but since you removed that predicate you don't need the parentheses either.