state?

state? returns true if all the given items have a valid state (not UNDEF or NULL).

Parameter	Description
`items`	One or more items to check
`things:`	Default: `false` - do not check for linked things status. When `things:` is set to `true`, only return true when all things linked to the items are in the ONLINE state.

Examples

if state? Item1, Item2 
  average = (Item1 + Item2)/2 # Neither Item1 nor Item2 is UNDEF/NULL
end

or in a rule guard

rule 'calculate' do
  changed Item1, Item2
  only_if { state? Item1, Item2 }
  run { logger.info "Average of Item1 and Item2: #{(Item1 + Item2) / 2}}" }
end

It can take an array of items:

calculated_items = [ Item1, Item2 ]

rule 'calculate' do
  changed calculated_items
  only_if { state? calculated_items }
  run { logger.info "Sum of Item1 and Item2: #{calculated_items.sum}" }
end