Nrthugu

Hello Liferay Experts,

I have a requirement where I need to stop an Admin from assigning a role, I am trying to implement this with a ModelListener.

Here is the code..

@Component(immediate = true, service = ModelListener.class)

public class TestUserModelListener extends BaseModelListener<User> {



    @Override

    public void onBeforeAddAssociation(Object classPK, String associationClassName, Objext accociationClassPK) throws ModelListenerException {

        // ...

        throw new ModelListenerException("User creation not allowed");

    }

}

When this code executes, the exception is thrown but the UI doesnt handle it correctly, the control panel Menus are not displayed and the exception message is not displayed to the user.

How to throw an exception and handle it correctly in UI and display error message to the user.

Thanks

M

Andre Albert already gave you the correct hints in the comments.
You should keep the ModelListener and override the ActionCommand additionally.

First, read the tutorial about Overriding MVC Comands. When implementing your custom Command, use Liferay's implemenation as basis (don't forget to add the higher service.ranking) and replace the catch block with something like this:

// I took the freedom and refactored Liferay's catch block a little bit

catch (NoSuchUserException | PrincipalException e) {

    SessionErrors.add(actionRequest, e.getClass());

    actionResponse.setRenderParameter("mvcPath", "/error.jsp");

} catch (MembershipPolicyException e) {

    SessionErrors.add(actionRequest, e.getClass(), e);

    actionResponse.setRenderParameter("mvcPath", "/edit_user.jsp");

    actionResponse.setRenderParameter("screenNavigationCategoryKey", UserFormConstants.CATEGORY_KEY_GENERAL);

    actionResponse.setRenderParameter("screenNavigationEntryKey", UserFormConstants.ENTRY_KEY_ROLES);

} catch (ForbiddenRoleAssociationException e) {

    // Here you can add a SessionError

    // and set some render parameters

} catch (Exception e) {

    throw e;

}

The ForbiddenRoleAssociationException does not exist yet. It's purpose is to distinguish this special case of a ModelListenerException from others which might not interest you. You'll have to implement it yourself. Just extend the ModelListenerException:

public class ForbiddenRoleAssociationException extends ModelListenerException {

    // here might be some constructors

}

Now adjust your ModelListener so that it throws your new ForbiddenRoeAssociationException:

@Component(immediate = true, service = ModelListener.class)

public class TestUserModelListener extends BaseModelListener<User> {



    @Override

    public void onBeforeAddAssociation(Object classPK, String associationClassName, Objext accociationClassPK) throws ModelListenerException {

        // ...

        throw new ForbiddenRoleAssociationException(); // or any other constructor

    }

}

This way you should be able to display error messages to admins (depending on your code in the catch block of the ForbiddenRoleAssociationException) and circumvent any other (programmatic) attempt to assign the Role as well.