Holon Platform tutorial: Web application

@DefaultView
@UIScope
@SpringView(name = "home") (1)
public class Home extends VerticalLayout implements View {

  private static final long serialVersionUID = 1L;

  @Autowired
  private Datastore datastore;

  @PostConstruct
  public void init() {
    Components.configure(this)
        // set full to view content
        .fullSize().spacing().add(Components.button().caption("Add new").styleName(ValoTheme.BUTTON_PRIMARY)
            // navigate to "manage" view
            .onClick(e -> ViewNavigator.require().toView("manage").navigate()).build())
        // build and add listing
        .addAndExpandFull(Components.listing.properties(PRODUCT)
            // setup data source using Datastore with 'products' table name target and product ID as pk
            .dataSource(datastore, TARGET, ID)
            // froze the ID column
            .frozenColumns(1)
            // set the ID column width and style
            .width(ID, 120).style(ID, "id-column")
            // when user clicks on a row, open the 'view' named View providing product id parameter
            .withItemClickListener((i, p, x, e) -> ViewNavigator.require().toView("view")
                .withParameter("id", i.getValue(ID)).navigate())
            // set full size and build
            .fullSize().build());
  }

}

@WindowView(windowWidth = "500px", windowHeigth = "400px")
@Caption("View product")
@SpringView(name = "view")
public class View extends VerticalLayout implements com.vaadin.navigator.View {

  private static final long serialVersionUID = 1L;

  @ViewParameter
  private long id;

  @Autowired
  private Datastore datastore;

  private final PropertyViewForm viewForm;

  public View() {
    super();
    Components.configure(this)
        // set margins and size full to view content
        .margin().fullSize()
        // add view form using Product property set
        .addAndExpandFull(viewForm = Components.view.form().fullSize().properties(PRODUCT).build()).add(
            // horizontal layout as bottom toolbar
            Components.hl().fullWidth().spacing().styleName(ValoTheme.WINDOW_BOTTOM_TOOLBAR)
                // EDIT action
                .add(Components.button().caption("Edit").fullWidth().styleName(ValoTheme.BUTTON_PRIMARY)
                    // navigate to "manage" view providing product id parameter
                    .onClick(e -> ViewNavigator.require().toView("manage").withParameter("id", id)
                        .navigate())
                    .build())
                // DELETE action
                .add(Components.button().caption("Delete").fullWidth()
                    .styleName(ValoTheme.BUTTON_DANGER)
                    // ask confirmation before delete
                    .onClick(e -> Components.questionDialog().message("Are you sure?")
                        .callback(answeredYes -> {
                          // if confirmed, delete the current form product PropertyBox
                          datastore.delete(TARGET, viewForm.getValue());
                          // navigate back
                          ViewNavigator.require().navigateBack();
                        }).open())
                    .build())
                .build());
  }

  @OnShow
  public void onShow() {
    // set the view form product value
    viewForm.setValue(
        // load product using id parameter
        datastore.query().target(TARGET).filter(ID.eq(id)).findOne(PRODUCT)
            // throw an exception if not found
            .orElseThrow(() -> new DataAccessException("Product not found: " + id)));
  }

}

@VolatileView
@SpringView(name = "manage")
public class Manage extends VerticalLayout implements com.vaadin.navigator.View {

  private static final long serialVersionUID = 1L;

  @ViewParameter
  private Long id;

  @Autowired
  private Datastore datastore;

  private PropertyInputForm form;

  private Button clearButton;

  @PostConstruct
  public void init() {
    Components.configure(this)
        // set margins and size full to view content
        .margin().fullSize().addAndExpandFull(
            // add a form using Product property set
            form = Components.input.form().fullSize().properties(PRODUCT)
                // set id as read-only
                .readOnly(ID)
                // set SKU as required
                .required(SKU)
                // add a validator to check DESCRIPTION with minimum 3 characters
                .withValidator(DESCRIPTION, Validator.min(3))
                // build the form
                .build())
        .add(Components.hl().margin().spacing()
            // SAVE action
            .add(Components.button().caption("Save").styleName(ValoTheme.BUTTON_PRIMARY)
                .onClick(e -> save()).build())
            // CLEAR action
            .add(clearButton = Components.button().caption("Clear")
                // clear the form
                .onClick(e -> form.clear()).build())
            .build());
  }

  @OnShow
  public void load() {
    // if id parameter is not null, we are in edit mode
    if (id != null) {
      // load the product data
      form.setValue(datastore.query().target(TARGET).filter(ID.eq(id)).findOne(PRODUCT)
          // throw an exception if a product with given id was not found
          .orElseThrow(() -> new DataAccessException("Data not found: " + id)));
    }
    // enable the Clear button if not in edit mode
    clearButton.setVisible(id == null);
  }

  private void save() {
    // check valid and get PropertyBox value
    form.getValueIfValid().ifPresent(value -> {

      // save and notify
      datastore.save(TARGET, value, DefaultWriteOption.BRING_BACK_GENERATED_IDS);
      // notify the saved id
      Notification.show("Saved [" + ((id != null) ? id : value.getValue(ID)) + "]");

      // go back home
      ViewNavigator.require().navigateToDefault();
    });

  }

}