How does and MVC grid and datasource determine which CRUD methods to use

[Casey]

How does an MVC grid, or it's datasource determine which controller methods to use when Creating, reading, updating and destroying data utilizing the datasource.sync() method?  I have a grid that that when sync is called, it is trying to use the update method on a new record which causes an error.  I can't figure out how to identify the new record to the grid and datasource so that it will use the create method instead.  Has anyone else experienced this issue?

[Casey]

Nevermind.  I found the isNew() and hasChanges() methods.