Is there a way to check if a property exists on a model?
var self = model.get("users."+userId);
if (! self.name.firstName){
//do something
}
This seems to work; however, you need to check each property one by one, since going to far down the chain might not exist.
so perhaps:
var self = model.get("users."+userId);
if (!self.name && !self.name.firstName){
//do something
}