When is it appropriate to extend the Domain Model in a Mendix application?

Extending the Domain Model in a Mendix application is appropriate when new dynamic data is needed in the app. The Domain Model represents the data structure of the application, including entities, their attributes, and relationships. Whenever there is a requirement to store or manage new types of information that were not previously accounted for, the Domain Model must be updated to include new entities or attributes that facilitate this new data.

For instance, if your application needs to capture additional details about users, products, or any other relevant aspect of the business that is dynamic and will change over time, the Domain Model should be updated accordingly. This ensures that the application can handle the required data operations, support additional functionalities, and retain data integrity.

In contrast, while introducing new user roles is essential for access control, it does not necessitate changes to the data model itself, but rather adjustments in security settings and permissions. Adding new themes or overhauling the user interface pertains primarily to the visual aspects and does not involve changes to how data is structured or managed within the application.