RE: Filter data on field change D365
The forms work exactly the same way in AX2012 and D365FO. The biggest difference is that if you are enhancing a Microsoft (or ISV) form, you need to develop your logic as extensions.
You can look at the standard forms to see how to implement this functionality. For example LedgerJournalTable form has a lookup that you can use to filter All/Not posted/Posted.
On this specific form, the filtering logic happens in another class but usually you can put such code directly on your form.
Your solution consists of three parts:
1) Hook in the modified method of the field, to trigger your functionality
2) Modify the form data source query according to user's selection in the field
3) Execute the data source query