Anna,
Mendix was designed that way as far back as I can remember. However, there are some changes in the works. The latest release of Mendix adds support for passing primitives from a page to nanoflows and microflows. In the future, the ability to pass primitives to pages may be added.
Current best practice would be to add a non persistable entity to your domain model, create an instance of that entity with the values you need and then pass that to your page.
Hope that helps,
Mike
Hey Anna,
Pop-ups accept only object parameters for data management. The design of objects allows validation and integrity rules across the application.
If you need to pass primitive data types, such as strings or integers, to a pop-up, a recommended practice is to create a non-persistent entity.
An example would be to create an entity called PopupData with attributes like test and test2. Then, use a microflow to prepare this entity: create an instance of PopupData, set its attributes with the desired primitive data, and open the pop-up with this entity as the object.
I hope this helps,
Ricardo Pereira