Google App maker user picker validation

Question

In App maker user picker widget is populating the users added in the organization. But it is not throwing any error when a valid value is not entered in the field. It just saves as an empty field. How to use the Validation display and Validation error message when an error encountered. I want display different error message when a particular error occurs.

Answer 1

First of all, you can enforce it on Model level by making the field required. Secondary, you can add your custom validation logic on UI:

// UserPicker onValidate event
if (widget.value === null || widget.value === '') {
  return 'validation error message goes here';
}

Be sure, that your form's submit button is bound to @widget.parent.parent.valid (it is default App Maker binding for forms) or forces validation on click:

// submit button onClick event for AM auto-generated form
if (widget.parent.parent.validate()) {
  widget.datasource.createItem();
}

This will trigger onValidate event for the UserPicker widget.