GXT validation feedback

Question

I have some POJO with JSR 303 validation like this one :

@NotNull
@Size(max = 80)
@Column(name = "trs_name")
private String name;

In the application, I render it with a GXT TextField wrapped in a GXT FieldLabel, inside a GWT Editor. If the validation fails, the FieldLabel automatically displays a red wave and a red flag :

And this is exactly what I need.

But for more complex validation like this one :

@Size(min = 1)
private Set<EnumRole> roles;

I created a custom Editor<Set<Enum>> :

public class EnumSetEditor<T extends Enum<T>> extends Composite implements LeafValueEditor<Set<T>> {


  private Map<T, CheckBox> map;

  public EnumSetEditor(Class<T> clazz) {
    FlowPanel panel = new FlowPanel();

    this.map = new HashMap<T, CheckBox>();
    for(T t : clazz.getEnumConstants()) {
      CheckBox cb = new CheckBox();
      cb.setBoxLabel(I18nEnum.i18nEnum(t)); //translates the enum
      panel.add(cb);
      map.put(t, cb);
    }
    this.initWidget(panel);
  }

  @Override
  public void setValue(Set<T> value) {
    for(Map.Entry<T, CheckBox> entry : map.entrySet()) {
      entry.getValue().setValue(value.contains(entry.getKey()));
    }
  }

  @Override
  public Set<T> getValue() {
    Set<T> result = new HashSet<T>();
    for(Map.Entry<T, CheckBox> entry : map.entrySet()) {
      if(entry.getValue().getValue()) {
        result.add(entry.getKey());
      }
    }
    return result;
  }
}

It is rendred like this :

The problem is that, even wrapped in a GXT FieldLabel, I have no feedback if no option is checked. Hence, the validation fails and the user has no feedback.

I thought that the GXT FieldLabel would automatically add the red flag on the right of the editor in case of validation failure.

1. Do I do something wrong ?
2. Is there a best practice to obtain this feedback ?

Answer 1

I finally found the solution myself : I believed that the FieldLabel handled the feedback itself but this is wrong.

1. My class must implement HasEditorErrors<Set<T>> so that method void showErrors(List<EditorError> errors) is called. I can do whatever I want in this case : display an icon, underline something etc.

2. There is a predefined class in GXT which handles the icon + the validation message : SideErrorHandler.

Hence, I modified the class like this :

public class EnumSetEditor<T extends Enum<T>> extends Composite implements LeafValueEditor<Set<T>>, HasEditorErrors<Set<T>> {

  //Added errorHandler attribute
  private SideErrorHandler errorHandler;

  public EnumSetEditor(Class<T> clazz) {

    ...
    //Initialize the ErrorHandler
    this.errorHandler = new SideErrorHandler(this);
  }

  /* 
   * Implemented showErrors(List<EditorError> errors)
   * I only delegate the errors to the ErrorHandler.
   */

  @Override
  public void showErrors(List<EditorError> errors) {
    if(errors.isEmpty()) {
      errorHandler.clearInvalid();
    } else {
      errorHandler.markInvalid(errors);
    }
  }
}