Enhanced Callback Functionality

If any callback is registered as an enhanced one, then all of the callbacks receive extra values as kwargs. These include the Dash application instance, a per-session dictionary that can contain anything suitable for inclusion in a standard Django session, and the Django User instance. The session state is per user session at the Django level, so it is shared across all of the Dash applications.

Changes made to any values contained within the initial state can also be persisted when using enhanced callbacks. This is a per-app-instance flag and, when set, the response of every callback is checked and persisted if it has changed. The second of the two apps below is configured in this manner; any changes made on this page should reappear if one visits a different page and then reloads this one. These changes can also be observed in the update timestamp or initial content json content of the model.