Documentation:OCLOperators collectNested

collectNested ( expr : OclExpression ) : Collection(T2)

Returns a collection containing all the elements contained in self on which we applied the OclExpression expr. The results won't be flattened. The type of the resulting collection depends on the type of self.

For the purpose of this example, we'll assume here that we have a Class Person with a reference children. Our model contains two persons such as person1.children = {James, Jane} and person2.children = {John}.

Expression	Result
self.persons->collectNested(children.firstname)	Sequence{Sequence{James, Jane}, Sequence{John}}