Vaadin multiselect OptionGroup and BeanFieldGroup

AbstractMultiselectToDTOConverter.java

public class AbstractMultiSelectToDTOConverter implements Converter<Object, List<BaseDTO>> {

    private static final long serialVersionUID = -7589634171531062832L;
    private BeanContainer<Long, BaseDTO> container;

    private final static List<BaseDTO> MODEL_TYPE_INSTANCE = new ArrayList<BaseDTO>();

    @SuppressWarnings("unchecked")
    public AbstractMultiSelectToDTOConverter(AbstractSelect field) {
        this.container = (BeanContainer<Long, BaseDTO>) field.getContainerDataSource();
    }

    @SuppressWarnings("unchecked")
    @Override
    public List<BaseDTO> convertToModel(Object itemIds, Class<? extends List<BaseDTO>> targetType, Locale locale) throws com.vaadin.data.util.converter.Converter.ConversionException {
        List<BaseDTO> models = new ArrayList<BaseDTO>();

        if (container.size() > 0) {
            for (Object itemId : ((HashSet<Object>) itemIds)) {
                if (container.containsId(itemId)) {
                    models.add(container.getItem(itemId).getBean());
                }
            }
        }

        return models;
    }

    @Override
    public Object convertToPresentation(List<BaseDTO> models, Class<? extends Object> targetType, Locale locale) throws com.vaadin.data.util.converter.Converter.ConversionException {
        List<Object> ids = new ArrayList<Object>();

        for (Object itemId : container.getItemIds()) {
            BaseDTO bean = container.getItem(itemId).getBean();

            for (Object model : models) {
                if (((BaseDTO) model).compareTo(bean)) {
                    ids.add(itemId);
                }
            }
        }

        return ids;
    }

    @SuppressWarnings("unchecked")
    @Override
    public Class<List<BaseDTO>> getModelType() {
        return (Class<List<BaseDTO>>) MODEL_TYPE_INSTANCE.getClass();
    }

    @Override
    public Class<Object> getPresentationType() {
        return Object.class;
    }

}

addCountryUI.java

// -----------------------------------------------------------------------------------
// Saving a country
//
// In this case, I must manually do the setCities() after the commit() of
/// the BeanFieldGroup, because it's done in the commit() itself.
// -----------------------------------------------------------------------------------
country = new CountryDTO();

formGroup = new BeanFieldGroup<CountryDTO>(CountryDTO.class);
formGroup.setItemDataSource(new BeanItem<CountryDTO>(country));
formGroup.buildAndBind("_Cities", "cities", OptionGroup.class);

// Set OptionGroup properties
OptionGroup citiesOptionGroup = (OptionGroup) formGroup.getField("cities");

// getCitiesContainer() returns a BeanContainer with all the cities in the DB,
// because thats what we need to be shown in the OptionGroup
citiesOptionGroup.setContainerDataSource(controller.getCitiesContainer());
citiesOptionGroup.setItemCaptionPropertyId("name");
citiesOptionGroup.setMultiSelect(true);
citiesOptionGroup.setConverter(new AbstractMultiSelectToDTOConverter(citiesOptionGroup));

// Attach it to a FormLayout
formLayout.addComponent(citiesOptionGroup);


// Later… on the click of the "save" button
try {
    Collection<Long> ids = (Collection<Long>) formGroup.getField("cities").getValue();

    formGroup.commit();
    country.setCities(controller.getCitiesById(ids));
    controller.saveCountry(country, successMessage);
} catch (CommitException e) {
    showWarningMessage("_Please fix marked fields and try again");
}

CityDTO.java

// Package, imports and so on…
@XmlRootElement
@Entity
@Table(name = "city", uniqueConstraints = @UniqueConstraint(name = "UNIQ_CITY", columnNames = { "city_id" }))
public class CityDTO extends BaseDTO {

    @Id
    @Column(name = "city_id")
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long cityId;

    @Column(name = "name", nullable = false)
    private String name;
    
    @ManyToMany(mappedBy = "cities")
    private List<CountryDTO> countries;
    
    // Getters and setters…
}

CountryDTO.java

// Package, imports and so on…
@XmlRootElement
@Entity
@Table(name = "role", uniqueConstraints = @UniqueConstraint(name = "UNIQ_COUNTRY", columnNames = { "country_id" }))
public class CountryDTO extends BaseDTO {

    @Id
    @Column(name = "country_id")
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long countryId;

    @Column(name = "name", nullable = false)
    private String name;

    @ManyToMany(fetch = FetchType.EAGER)
    @JoinTable(name = "country_city", joinColumns = { @JoinColumn(name = "country_id", nullable = true, updatable = false) }, inverseJoinColumns = { @JoinColumn(name = "city_id", nullable = true, updatable = false) })
    private List<CityDTO> cities;
    
    // Getters and setters…
}

editCountryUI.java

// -----------------------------------------------------------------------------------
// Existing country with cities
//
// Same process here, except we are working with an existing DB CountryDTO, which
// happens to have some CityDTO inside.
//
// Here, the situation is that the cities of the country are not being checked in
// the OptionGroup. And that happens because the "set" of the OptionGroup is not being
// called. I know this because the methods on the OptionGroup converter are not being
// called neither.
//
// So I ended up setting the value of the OptionGroup manually, like this;
//
// OptionGroup permissionsOptionGroup = (OptionGroup) formGroup.getField("cities");
// permissionsOptionGroup.setValue(controller.getSelectedCities(country));
//
// Notice that getSelectedCities() returns a List<Long> with the IDs of the cities
// inside the given country.
//
// Following this path, everything works as expected. The OptionGroup gets the right
// options checked.
// -----------------------------------------------------------------------------------
country = countryService.findOne(1L); // Get sample CountryDTO

formGroup = new BeanFieldGroup<CountryDTO>(CountryDTO.class);
formGroup.setItemDataSource(new BeanItem<CountryDTO>(country));
formGroup.buildAndBind("_Cities", "cities", OptionGroup.class);

// Set OptionGroup properties
OptionGroup citiesOptionGroup = (OptionGroup) formGroup.getField("cities");

// getCitiesContainer() returns a BeanContainer with all the cities in the DB,
// because thats what we need to be shown in the OptionGroup
citiesOptionGroup.setContainerDataSource(controller.getCitiesContainer());
citiesOptionGroup.setItemCaptionPropertyId("name");
citiesOptionGroup.setMultiSelect(true);
citiesOptionGroup.setConverter(new AbstractMultiSelectToDTOConverter(citiesOptionGroup));

// Attach it to a FormLayout
formLayout.addComponent(citiesOptionGroup);