A custom
controller is an
Apex class that implements all of the logic for a page without leveraging a
standard controller. Use custom controllers when you want your Visualforce page
to run entirely in system mode, which does not enforce the permissions and
field-level security of the current user.
A controller
extension is an Apex
class that extends the functionality of a standard or custom controller. Use
controller extensions when:
·
You want to leverage the built-in functionality of a standard
controller but override one or more actions, such as edit, view, save, or
delete.
·
You want to add new actions.
·
You want to build a Visualforce page that respects user
permissions. Although a controller extension class executes in system mode, if
a controller extension extends a standard controller, the logic from the
standard controller does not execute in system mode. Instead, it executes in
user mode, in which permissions, field-level security, and sharing rules of the
current user apply.
