How to check if variable empty in Drools Templates

Question

I'm using Drools templates to generate Rules from a spreadsheet. I have some problems with empty cell. Does anybody know how to check if a cell or the variable is empty? This is the template:

template header
pid
department
maxAmount
storeId

package X.X.X

declare MaxAmountStore
    amount : Integer    
    storeId : String
end

template "FOO"
rule "MaxAmountStore_@{row.rowNumber}"
        when
            Product(pid == "@{pid}")
            Product(departmentId == "@{department}")
        then
            System.out.println("New MaxAmountStore: @{maxAmount} (store: @{storeId})");
            insert( new MaxAmountStore(@{maxAmount}, "@{storeId}"));
    end
end

Is it possible to have an empty storeId?

Answer 1

I think you need this: if there's nothing in the cell, you don't care about the departmentId value and want to fire the rule based on pid alone.

template "FOO"
rule "MaxAmountStore_@{row.rowNumber}"
when
    Product( pid == "@{pid}"&& 
             ("" == "@{department}" || departmentId == "@{department}") )
then
    ...
end