What is the best way to ensure that mandatory Customer data fields are filled before sending data to the server?

The best way to ensure that mandatory Customer data fields are filled before sending data to the server is to set the Built-in validations of the Save button to Yes and check if the Form's Valid property is True.

This approach leverages the built-in validation mechanisms provided by the OutSystems platform, which automatically checks for required fields and other constraints defined on the entities. By setting the Save button's built-in validations to Yes, you enable these checks to be performed when the button is clicked. Once this is done, checking the Form's Valid property lets you efficiently determine if all required fields have been correctly filled out.

If the Form's Valid property returns True, it indicates that all mandatory fields have been validated successfully and are ready to be sent to the server. This step is critical as it acts as a final validation layer before performing any server-side operations, thereby preventing redundant data submissions for invalid entries.

Utilizing this built-in validation method helps reduce boilerplate code while promoting cleaner and more maintainable logic in your application. It also ensures that client-side validations are in sync with the server-side validation rules, enhancing overall data integrity.