I have this use case: an Order can contain one or more items... each item is characterized by one or more measures. They are described by this simple pojo class. public class Order{ protected List<Item> itemList; public void setItemList (List<Item> itemList) { ... } public List<Item> getItemList() { ... } } public class Item { protected List<Measure> measureList; public void setMeasureList (List<Measure> measureList) { ... } public List<Measure> getMeasureList() { ... } } public class Measure { protected int measure; public getMeasure() { ... } public setMeasure() { ... } } Supposing i have in my Working Memory an Order containing 2 items. The first item contains 5 measures, the second one instead contains 12 Measures. I'd like to write a rule using MVEL (for the assumptions), specifying WHEN each ITEM has more than 11 measures THEN system.out.println ("order is valid"); How can i write the assumption? It's important to use MVEL ... (is it necessary to use accumulate? from? or what?) Really thanks. -- View this message in context: http://drools.46999.n3.nabble.com/Counting-Number-of-Items-in-NESTED-LIST... Sent from the Drools: User forum mailing list archive at Nabble.com. _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users

thanks a lot laune... mvel it's necessary for now as in my editor there is still not che possibility to set the language for building rules.