I am applying some basic validation to an app. I have applied it via the Domain Model, by double-clicking on the Entities within it. I’ve added, for example, ‘Required’ and a meaningful error message. I’ve added my validation via the Domain Model, as opposed to the form attributes, as the Mendix training guide states “Make sure that you only add usability logic to the frontend, and not security logic, because a UI is easily bypassed”. I then run locally and view the app to test the validation. If I try to enter details that fail validation, instead of an error message, the form simply disappears. If I try to edit details for existing people it’s the same thing; the amend form disappears but the persons’ details (correctly) aren’t updated, there's just no way for a user to know why. Am I missing some association that’s preventing me from getting an error message displayed on the form?
The way you have set up the domain model validation should work the way you expect, so there are a few things to check to get more details about what is wrong.
1) After you enter incorrect details, are you hitting a 'save' button in your app? If so, does that Save button trigger a custom microflow? The validations entered will only be triggered when you try to commit those entities.
2) When does the form disappear? Is it happening right after you leave the field with the entered data?
3) Are there any errors in your console?
Nothing jumps out as being obviously wrong here. Can you post a screenshot or two?