A question on assertion please

Sorry to bother you again, I have a question on assertion please

I use SoapUI Pro (and am testing API Ready now) to do functional test on medical rules, here's a simple example:

Medical Rule 123: A child who's 2 years old should have MMR vaccine

In the xml request I offer a child's date of birth, ruleID=123, if the child is 2 years old (as of today), it displays the ruleID of123 in the response and send an alert to the child's doctor, if the child is not 2 years old, it doesn't display the ruleID and no alert is generated

For the data source I use Excel spreadsheet like:

DOB                         RuleID           isEligible

2013-01-01          123                true            --- 2 years old

2014-01-01          123                false           --- not 2 years old

2013-01-02          123                false           --- 2 years old

I've created the related properties "DOB" and "ruleID" for data driven test, and I'd like to add an assertion on ruleID in response, if I have ruleID 123 displayed in response then the child is eligible for vaccine

I was thinking to use "contains" (for ruleID=123) assertion, for the above 1st child, the response contains ruleID=123, so the child is eligible for vaccine, and since I set isEligible to true, this test case should pass; for the 2nd child, the response doesn't contain ruleID=123, so the child is not eligible and since I set isEligible to false, this test case should also pass; the 3rd child is also 2 years old but I set isEligible to false, so this test case should fail

How do I implement "isEligible" comparing with the assertion result please?

Thanks a lot for help

Jerry