Exception JSF Delete from Database

Question

I have a problem with my exception handling in JSF.

I want to show an error message on my JSF page when the user can not delete an entry in the database.

<h:message for="deleteButton"/>
<h:commandButton id="deleteButton" value="Delete" action="#{filmView.deleteRow(film)}"/>

public void deleteRow(Film deleteTemp) {
  filmService.delete(deleteTemp.getFilmId());
}

public void delete(int id) {
  try {
    em.createQuery("delete from Film where film_id=" + id).executeUpdate();
  } catch (Exception e) {
    FacesContext.getCurrentInstance().addMessage("", new FacesMessage(
    "Removing dataset(ID:" 
     + id + ") is not possible, because it's used in another dataset!"));
    }
}

Is it possible to get this error message into the JSF page and if yes is this better, because I heard that how I do it right now, it is not a good solution.

Why is not a good solution? Does it work or not? Try to identify your problem: is it jpa related or jsf? Can you catch the exception? Can you show a Faces Message? — perissf, Nov 12 '18 at 16:56
@perissf It is working, but my problem is that i went from the bottom layer directly to the view and not go from one layer to another and I thought it would be possible to do the exception handling directly on the view. — Felix, Nov 12 '18 at 17:11

ℛɑƒæĿᴿᴹᴿ · Accepted Answer · 2020-06-26T20:56:57.837

Ideally your ManagedBean should handle screen messages:

The best way is throw the error from DAO to your Service layer.
On Service layer you can throw again to your ManagedBean and show the message.

On your FilmDAO.java:

public void delete(int id) throws Exception {
    em.createQuery("delete from Film where film_id=" + id).executeUpdate();
}

On your FilmService.java:

public void delete(int id) throws Exception {
    filmDAO.delete(id);
}

On your FilmMB.java:

try {
  filmService.delete(id);
} catch (Exception e) {
  FacesContext.getCurrentInstance().addMessage("", 
    new FacesMessage("Removing dataset(ID:" + id + ") is not possible, 
                      because it's used in another dataset!"));
}

Exception JSF Delete from Database

1 Answers1