Question

This does not work, it sets the defaultView as “bar”, but then never updates to “foo” when the ajax request is completed. I tried to set this as a dependentObservable but didn’t have any more luck. Am I missing something obvious or am I trying to stretch namespaces too far?

$.get("/players/summary", function(json) {
  var playerViewModel = ko.mapping.fromJS(json);
  dateViewModel.defaultDate = "foo";
  ko.applyBindings(playerViewModel, 'player');
});

var dateViewModel = {
  defaultDate: ko.observable("bar")
};

ko.applyBindings(dateViewModel, 'date');

Answer 1

You are not setting “foo” correctly. You should write:

dateViewModel.defaultDate("foo"); 

So you have:

$.get("/players/summary", function(json) { 
  var playerViewModel = ko.mapping.fromJS(json); 
  dateViewModel.defaultDate("foo"); // <--- Set foo using getter setter syntax
  ko.applyBindings(playerViewModel, 'player'); 
}); 

var dateViewModel = { 
  defaultDate: ko.observable("bar") 
}; 

ko.applyBindings(dateViewModel, 'date'); 

This should fix it, but if you still have problems then I would look at definining dateViewModel before your $.get call.