Given a object such as Person which has an optional child object such as IdentityDetails (1:0/1) I cant get this to work properly. I just dont want to show the template if identitysection is null. 

Even when hasIdentitySection returns false this produces an exception because it tries to evaluate identitySection which is null

<div data-bind="visible: hasIdentitySection">           
 <div data-bind="source: identitySection" data-template="identity-template"></div> </div>