New field missing in model for normal page loading,but exist when refresh the page.

[stevengpn]

console.log(this.model.has('newField')); //return false for normal page loading (enter by clicking link)
//but returns true when refreshing the page (force-reload)

What could be the issue? time lagging?
Is there any way to use call-back to retrieve data from the model? this.model.get("fieldName")

Cheers,
Steven