Hi,
Thanks for the proposed solution for individual field validation.
Checks and validations on each field are not always sufficient. A final check on the data model to accept or not a record is often required.
Even if the individual values in the fields are accepted, they may not meet other business rules.
A mechanism to refuse to save (post) changes and possibly return to initial values (cancel) would be very useful.
The Dataset can be a proxy class over the data model.
In the data clases raising an exception in the save method when requirments are not fit, allows me to keep separate business rules from the UI.