Hi Chika,
You could do the following:
- Create a non persistent entity and associate it to the entity (the details of which you show in datagrid) so a 1-* association.
- This non persistent entity should have your category either in the form of enumeration if its static or another association to your NPE if its stored in an entity of its own.
- When the user clicks on multiple objects in the datagrid and clicks on the button → write custom logic in the called microflow
- In the microflow, a parameter to pass the list selected from the datagrid, and create an object of your non persistent entity and associate all the details. Pass this NPE object to the page where you can select the category inside the dataview.
- On this page another button to process your data where you could loop through all the associated objects and set the category.
If you’ve not already taken a course from Mendix academy, go ahead and take them, it will benefit a lot as such concepts are included:
https://academy.mendix.com/link/paths/31/Become-a-Rapid-Developer
In case you don’t know what is NPE take a look at this → https://docs.mendix.com/refguide/persistability#non-persistable
Hope this helps