Raise an error to the user via Model Admin & DataObject::onBeforeDelete()

Question

Given I'm using Model Admin to manage a Customer DataObject and I have code like this, taken from the SilverStripe docs:

public function onBeforeDelete() {
    if ($this->Orders()->Count() > 0) {
        user_error("Cannot delete a Customer with Orders", E_USER_ERROR);
        exit();
    }
    parent::onBeforeDelete();
}

When I try to delete a Customer with Orders via Model Admin all I get is a JavaScript alert that says "An error occured while fetching data from the server. Please try again later" and a notification on the top right of

Error at line 42 of /var/www/mysite/code/dataobjects/Customer.php

How do I get a nice message to come back to Model Admin saying "Cannot delete a Customer with Orders"?

Answer 1

You could try this:

public function canDelete($member=null) {
    if ($this->Orders()->Count() > 0) {
        return false;
    }
    return parent::canDelete($member);

}

This will remove the delete button altogether, but you'd have to make it clear to your users why in another way.