Optional fields are not correctly validated

[matteocng]

If you ran the app below, inserted 'a' in all six email, link and quantity fields and saved, the red error label 'Required' would appear exclusively below the required() fields. Then, if you correctly filled in just the three required() fields, the save action would complete by saving 'null' in the DB for the three optional fields. It would be nice to abort the save action and show an error label below 'invalid' optional fields too.

We could also show 'Invalid data' instead of 'Required' to distinguish between 'empty required() field' and 'any field with validation error'.

A.app({
  appName: "Validation behaviour",
  appIcon: "heart",
  menuItems: [
    {
      name: "Gifts",
      icon: "gift",
      entityTypeId: "Gift",
    }
  ],
  entities: function(Fields) {
    return {
      Gift: {
        title: 'Gifts',
        fields: {
          item: Fields.text("Item").required(),
          quantity: Fields.integer("Quantity"),
          quantity_required: Fields.integer("Quantity Required").required(),
          email: Fields.email("Email"),
          email_required: Fields.email("Email Required").required(),
          link: Fields.email("Link"),
          link_required: Fields.email("Link Required").required()
        }
      }
    }
  }
});